diff --git a/code-samples/business/address.php b/code-samples/business/address.php
new file mode 100644
index 0000000..455ed8e
--- /dev/null
+++ b/code-samples/business/address.php
@@ -0,0 +1,76 @@
+<?php
+
+require_once('../../lib/autoload.php');
+
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => '<your-public-key>',
+    'privateKey' => '<your-private-key>',
+]);
+
+echo "FasterPay Address API Examples\n";
+echo "==============================\n\n";
+
+// Example 1: Get address fields for United States
+echo "1. Getting address fields for United States\n";
+echo "--------------------------------------------\n";
+
+try {
+    $addressFieldsResponse = $businessGateway->addressService()->getAddressFields('US');
+
+    if ($addressFieldsResponse->isSuccessful()) {
+        echo "Address fields retrieved successfully\n";
+        $data = $addressFieldsResponse->getDecodeResponse();
+        $countryCode = isset($data['data']['country_code']) ? $data['data']['country_code'] : 'US';
+        $fields = isset($data['data']['fields']) ? $data['data']['fields'] : [];
+        $subdivisions = isset($data['data']['subdivisions']) ? $data['data']['subdivisions'] : [];
+
+        echo "  Country: $countryCode\n";
+        echo "  Required fields:\n";
+
+        foreach ($fields as $field) {
+            $type = isset($field['type']) ? $field['type'] : 'text';
+            $label = isset($field['label']) ? $field['label'] : '';
+            $name = isset($field['name']) ? $field['name'] : '';
+            echo "    - $label ($name): $type\n";
+        }
+
+        echo "  States/subdivisions: " . count($subdivisions) . " available\n";
+        echo "  Example states: ";
+        $exampleStates = array_slice($subdivisions, 0, 3);
+        foreach ($exampleStates as $state) {
+            echo $state['name'] . ' (' . $state['code'] . ') ';
+        }
+        echo "\n";
+    } else {
+        echo "Error: " . $addressFieldsResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 2: Get address fields for Canada
+echo "2. Getting address fields for Canada\n";
+echo "------------------------------------\n";
+
+try {
+    $canadaFieldsResponse = $businessGateway->addressService()->getAddressFields('CA');
+
+    if ($canadaFieldsResponse->isSuccessful()) {
+        echo "Canadian address fields retrieved\n";
+        $data = $canadaFieldsResponse->getDecodeResponse();
+        $fields = isset($data['data']['fields']) ? $data['data']['fields'] : [];
+
+        echo "  Canada requires " . count($fields) . " fields:\n";
+        foreach ($fields as $field) {
+            echo "    - " . (isset($field['label']) ? $field['label'] : 'Unknown') . "\n";
+        }
+    } else {
+        echo "Error: " . $canadaFieldsResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\nAddress API examples completed!\n";
diff --git a/code-samples/business/contact.php b/code-samples/business/contact.php
new file mode 100644
index 0000000..2a967a6
--- /dev/null
+++ b/code-samples/business/contact.php
@@ -0,0 +1,193 @@
+<?php
+
+require_once('../../lib/autoload.php');
+
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => '<your-public-key>',
+    'privateKey' => '<your-private-key>',
+]);
+
+echo "FasterPay Contact API Examples\n";
+echo "===============================\n\n";
+
+// Example 1: Create a new individual contact
+echo "1. Creating a new individual contact\n";
+echo "------------------------------------\n";
+
+$contactData = [
+    'email' => 'john.smith@example.com',
+    'phone' => '2015550124',
+    'phone_country_code' => 'US',
+    'first_name' => 'John',
+    'last_name' => 'Smith',
+    'country' => 'US',
+    'favorite' => true
+];
+
+try {
+    $contactResponse = $businessGateway->contactService()->createContact($contactData);
+
+    if ($contactResponse->isSuccessful()) {
+        echo "Contact created successfully\n";
+        $responseData = $contactResponse->getDecodeResponse();
+        $contactId = isset($responseData['data']['id']) ? $responseData['data']['id'] : 'CT-' . time();
+        echo "  Contact ID: " . $contactId . "\n";
+        echo "  Name: " . $contactData['first_name'] . " " . $contactData['last_name'] . "\n";
+        echo "  Email: " . $contactData['email'] . "\n";
+        echo "  Phone: " . $contactData['phone'] . "\n";
+        echo "  Country: " . $contactData['country'] . "\n";
+    } else {
+        echo "Error: " . $contactResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 2: Create another contact (for listing)
+echo "2. Creating another contact (for listing)\n";
+echo "---------------------------\n";
+
+$secondContactData = [
+    'email' => 'jane.doe@example.com',
+    'phone' => '2015550987',
+    'phone_country_code' => 'US',
+    'first_name' => 'Jane',
+    'last_name' => 'Doe',
+    'country' => 'US',
+    'favorite' => false
+];
+
+try {
+    $secondContactResponse = $businessGateway->contactService()->createContact($secondContactData);
+
+    if ($secondContactResponse->isSuccessful()) {
+        echo "Second contact created successfully\n";
+        $responseData = $secondContactResponse->getDecodeResponse();
+        $secondContactId = isset($responseData['data']['id']) ? $responseData['data']['id'] : 'CT-2-' . time();
+        echo "  Contact ID: " . $secondContactId . "\n";
+        echo "  Name: " . $secondContactData['first_name'] . " " . $secondContactData['last_name'] . "\n";
+        echo "  Email: " . $secondContactData['email'] . "\n";
+        echo "  Phone: " . $secondContactData['phone'] . "\n";
+    } else {
+        echo "Error: " . $secondContactResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 3: Get contact details
+echo "3. Getting contact details\n";
+echo "--------------------------\n";
+
+try {
+    $detailsResponse = $businessGateway->contactService()->getContact($contactId);
+
+    if ($detailsResponse->isSuccessful()) {
+        echo "Contact details retrieved successfully\n";
+        $details = $detailsResponse->getDecodeResponse();
+        
+        if (isset($details['data'])) {
+            $contact = $details['data'];
+            echo "  ID: " . (isset($contact['id']) ? $contact['id'] : 'N/A') . "\n";
+            echo "  Name: " . (isset($contact['first_name']) ? $contact['first_name'] : '') . " " . (isset($contact['last_name']) ? $contact['last_name'] : '') . "\n";
+            echo "  Email: " . (isset($contact['email']) ? $contact['email'] : 'N/A') . "\n";
+            echo "  Phone: " . (isset($contact['phone_full_number']) ? $contact['phone_full_number'] : 'N/A') . "\n";
+            echo "  Country: " . (isset($contact['country']) ? $contact['country'] : 'N/A') . "\n";
+        }
+    } else {
+        echo "Error: " . $detailsResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 4: Update contact
+echo "4. Updating contact information\n";
+echo "-------------------------------\n";
+
+$updateData = [
+    'phone' => '2015550125',
+    'phone_country_code' => 'US',
+    'favorite' => false,
+    'first_name' => 'Jonathan'
+];
+
+try {
+    $updateResponse = $businessGateway->contactService()->updateContact($contactId, $updateData);
+
+    if ($updateResponse->isSuccessful()) {
+        echo "Contact updated successfully\n";
+        echo "  Contact ID: " . $contactId . "\n";
+        echo "  New phone: " . $updateData['phone'] . "\n";
+        echo "  Updated name: " . $updateData['first_name'] . "\n";
+        echo "  Favorite: " . ($updateData['favorite'] ? 'Yes' : 'No') . "\n";
+    } else {
+        echo "Error: " . $updateResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 5: List contacts with filters
+echo "5. Listing contacts with filters\n";
+echo "--------------------------------\n";
+
+$filters = [
+    'per_page' => 20,
+    'page' => 1
+];
+
+try {
+    $listResponse = $businessGateway->contactService()->listContacts($filters);
+
+    if ($listResponse->isSuccessful()) {
+        echo "Contact list retrieved successfully\n";
+        
+        $listData = $listResponse->getDecodeResponse();
+        if (isset($listData['data']['data']) && is_array($listData['data']['data'])) {
+            $contacts = $listData['data']['data'];
+            echo "  Found " . count($contacts) . " contacts\n";
+            
+            foreach ($contacts as $contact) {
+                $name = (isset($contact['first_name']) ? $contact['first_name'] : '') . ' ' . (isset($contact['last_name']) ? $contact['last_name'] : '');
+                $email = isset($contact['email']) ? $contact['email'] : 'No email';
+                echo "    - " . trim($name) . " (" . $email . ")\n";
+            }
+        }
+    } else {
+        echo "Error: " . $listResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 6: Delete a contact
+echo "6. Deleting a contact\n";
+echo "---------------------\n";
+
+$contactToDelete = isset($secondContactId) ? $secondContactId : 'CT-DELETE-' . time();
+
+try {
+    $deleteResponse = $businessGateway->contactService()->deleteContact($contactToDelete);
+
+    if ($deleteResponse->isSuccessful()) {
+        echo "Contact deleted successfully\n";
+        echo "  Deleted Contact ID: " . $contactToDelete . "\n";
+    } else {
+        echo "Error: " . $deleteResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\nContact API examples completed!\n";
\ No newline at end of file
diff --git a/code-samples/business/e-invoice/discount.php b/code-samples/business/e-invoice/discount.php
new file mode 100644
index 0000000..6572b6b
--- /dev/null
+++ b/code-samples/business/e-invoice/discount.php
@@ -0,0 +1,226 @@
+<?php
+
+require_once('../../../lib/autoload.php');
+
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => '<your-public-key>',
+    'privateKey' => '<your-private-key>',
+]);
+
+echo "FasterPay Invoice Discount API Examples\n";
+echo "==========================================\n\n";
+
+// Example 1: Create a flat discount
+echo "1. Creating a flat discount\n";
+echo "---------------------------\n";
+
+$flatDiscountData = [
+    'name' => 'Early Bird Discount',
+    'type' => 'flat',
+    'value' => 10.00,
+    'currency' => 'USD',
+    'description' => '$10 discount for early payment'
+];
+
+try {
+    $discountResponse = $businessGateway->invoiceDiscountService()->createDiscount($flatDiscountData);
+
+    if ($discountResponse->isSuccessful()) {
+        echo "Flat discount created successfully\n";
+        $responseData = $discountResponse->getDecodeResponse();
+        $discountId = isset($responseData['data']['id']) ? $responseData['data']['id'] : 'DC-' . time();
+        echo "  Discount ID: " . $discountId . "\n";
+        echo "  Name: " . $flatDiscountData['name'] . "\n";
+        echo "  Type: " . $flatDiscountData['type'] . "\n";
+        echo "  Value: $" . number_format($flatDiscountData['value'], 2) . " " . $flatDiscountData['currency'] . "\n";
+        echo "  Description: " . $flatDiscountData['description'] . "\n";
+    } else {
+        echo "Error: " . $discountResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 2: Create a percentage discount
+echo "2. Creating a percentage discount\n";
+echo "---------------------------------\n";
+
+$percentageDiscountData = [
+    'name' => 'Volume Discount',
+    'type' => 'percentage',
+    'value' => 15,
+    'description' => '15% discount for bulk orders'
+];
+
+try {
+    $volumeResponse = $businessGateway->invoiceDiscountService()->createDiscount($percentageDiscountData);
+
+    if ($volumeResponse->isSuccessful()) {
+        echo "Percentage discount created successfully\n";
+        $responseData = $volumeResponse->getDecodeResponse();
+        $volumeDiscountId = isset($responseData['data']['id']) ? $responseData['data']['id'] : 'DC-VOLUME-' . time();
+        echo "  Discount ID: " . $volumeDiscountId . "\n";
+        echo "  Name: " . $percentageDiscountData['name'] . "\n";
+        echo "  Type: " . $percentageDiscountData['type'] . "\n";
+        echo "  Value: " . $percentageDiscountData['value'] . "%\n";
+        echo "  Description: " . $percentageDiscountData['description'] . "\n";
+    } else {
+        echo "Error: " . $volumeResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 3: Create loyalty discount
+echo "3. Creating loyalty discount\n";
+echo "----------------------------\n";
+
+$loyaltyDiscountData = [
+    'name' => 'Loyalty Customer Discount',
+    'type' => 'percentage',
+    'value' => 25,
+    'description' => '25% discount for loyal customers'
+];
+
+try {
+    $loyaltyResponse = $businessGateway->invoiceDiscountService()->createDiscount($loyaltyDiscountData);
+
+    if ($loyaltyResponse->isSuccessful()) {
+        echo "Loyalty discount created successfully\n";
+        $responseData = $loyaltyResponse->getDecodeResponse();
+        $loyaltyDiscountId = isset($responseData['data']['id']) ? $responseData['data']['id'] : 'DC-LOYALTY-' . time();
+        echo "  Discount ID: " . $loyaltyDiscountId . "\n";
+        echo "  Name: " . $loyaltyDiscountData['name'] . "\n";
+        echo "  Type: " . $loyaltyDiscountData['type'] . "\n";
+        echo "  Value: " . $loyaltyDiscountData['value'] . "%\n";
+        echo "  Description: " . $loyaltyDiscountData['description'] . "\n";
+    } else {
+        echo "Error: " . $loyaltyResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 4: Get discount details
+echo "4. Retrieving discount details\n";
+echo "------------------------------\n";
+
+$testDiscountId = isset($discountId) ? $discountId : 'DC-250527-WZX0';
+
+try {
+    $getDiscountResponse = $businessGateway->invoiceDiscountService()->getDiscount($testDiscountId);
+
+    if ($getDiscountResponse->isSuccessful()) {
+        echo "Discount details retrieved successfully\n";
+        $discountData = $getDiscountResponse->getDecodeResponse();
+        if (isset($discountData['data'])) {
+            $discount = $discountData['data'];
+            echo "  Discount ID: " . (isset($discount['id']) ? $discount['id'] : $testDiscountId) . "\n";
+            echo "  Name: " . (isset($discount['name']) ? $discount['name'] : 'N/A') . "\n";
+            echo "  Type: " . (isset($discount['type']) ? $discount['type'] : 'N/A') . "\n";
+            echo "  Value: " . (isset($discount['value']) ? $discount['value'] : 'N/A') . "\n";
+            if (isset($discount['currency'])) {
+                echo "  Currency: " . $discount['currency'] . "\n";
+            }
+            echo "  Description: " . (isset($discount['description']) ? $discount['description'] : 'N/A') . "\n";
+        }
+    } else {
+        echo "Error: " . $getDiscountResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 5: Update discount
+echo "5. Updating discount\n";
+echo "--------------------\n";
+
+$updateDiscountData = [
+    'name' => 'Updated Early Bird Discount',
+    'description' => 'Updated early payment discount with better terms',
+    'value' => 15.00
+];
+
+try {
+    $updateResponse = $businessGateway->invoiceDiscountService()->updateDiscount($testDiscountId, $updateDiscountData);
+
+    if ($updateResponse->isSuccessful()) {
+        echo "Discount updated successfully\n";
+        echo "  Discount ID: " . $testDiscountId . "\n";
+        echo "  Updated Name: " . $updateDiscountData['name'] . "\n";
+        echo "  Updated Value: $" . number_format($updateDiscountData['value'], 2) . "\n";
+        echo "  Updated Description: " . $updateDiscountData['description'] . "\n";
+    } else {
+        echo "Error: " . $updateResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 6: List discounts
+echo "6. Listing discounts\n";
+echo "--------------------\n";
+
+$filters = [
+    'per_page' => 20,
+    'page' => 1
+];
+
+try {
+    $listResponse = $businessGateway->invoiceDiscountService()->listDiscounts($filters);
+
+    if ($listResponse->isSuccessful()) {
+        echo "Discount list retrieved successfully\n";
+        $listData = $listResponse->getDecodeResponse();
+        if (isset($listData['data']['data']) && is_array($listData['data']['data'])) {
+            echo "  Found " . count($listData['data']['data']) . " discounts:\n";
+            foreach ($listData['data']['data'] as $discount) {
+                $id = isset($discount['id']) ? $discount['id'] : 'Unknown';
+                $name = isset($discount['name']) ? $discount['name'] : 'Unnamed';
+                $type = isset($discount['type']) ? $discount['type'] : 'Unknown';
+                $value = isset($discount['value']) ? $discount['value'] : '0';
+                $currency = isset($discount['currency']) ? ' ' . $discount['currency'] : '';
+                echo "    - " . $name . " (" . $id . ") - " . $type . ": " . $value . $currency . "\n";
+            }
+        }
+    } else {
+        echo "Error: " . $listResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 7: Delete discount
+echo "7. Deleting discount\n";
+echo "--------------------\n";
+
+$deleteTestDiscountId = isset($loyaltyDiscountId) ? $loyaltyDiscountId : 'DC-DELETE-' . time();
+
+try {
+    $deleteResponse = $businessGateway->invoiceDiscountService()->deleteDiscount($deleteTestDiscountId);
+
+    if ($deleteResponse->isSuccessful()) {
+        echo "Discount deleted successfully\n";
+        echo "  Deleted Discount ID: " . $deleteTestDiscountId . "\n";
+    } else {
+        echo "Error: " . $deleteResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+echo "\nInvoice Discount API examples completed!\n";
\ No newline at end of file
diff --git a/code-samples/business/e-invoice/invoice.php b/code-samples/business/e-invoice/invoice.php
new file mode 100644
index 0000000..2280523
--- /dev/null
+++ b/code-samples/business/e-invoice/invoice.php
@@ -0,0 +1,479 @@
+<?php
+
+/**
+ * FasterPay Invoice API - Complete Component Creation & Invoice Examples
+ * Creates invoice components first to get their IDs, then uses those IDs for invoices
+ */
+
+require_once('../../../lib/autoload.php');
+
+// Initialize BusinessGateway
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => 'your_public_key',
+    'privateKey' => 'your_private_key',
+]);
+
+// Store component IDs for later use
+$createdTemplateId = null;
+$createdTaxId = null;
+$createdDiscountId = null;
+$createdProductId = null;
+$createdContactId = null;
+
+// ===================================================================
+// CREATE CONTACT FIRST
+// ===================================================================
+
+$contactData = [
+    'email' => 'john.smith@example.com',
+    'phone' => '2015550124',
+    'phone_country_code' => 'US',
+    'first_name' => 'John',
+    'last_name' => 'Smith',
+    'country' => 'US',
+    'favorite' => true
+];
+
+try {
+    $response = $businessGateway->contactService()->createContact($contactData);
+
+    if ($response->isSuccessful()) {
+        $responseData = $response->getDecodeResponse();
+        $createdContactId = $responseData['data']['id'];
+        echo 'Contact created: ' . $createdContactId . "\n";
+    } else {
+        echo 'Error creating contact: ' . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo 'Exception creating contact: ' . $e->getMessage() . "\n";
+}
+
+// ===================================================================
+// CREATE TEMPLATE COMPONENT
+// ===================================================================
+
+$templateData = [
+    'name' => 'Project Template',
+    'footer' => 'Thank you for your business!',
+    'colors' => [
+        'primary' => '#2563eb',
+        'secondary' => '#f8fafc'
+    ],
+    'localized_address' => [
+        'address_line1' => '123 Business Ave',
+        'locality' => 'San Francisco',
+        'administrative_area' => 'CA',
+        'postal_code' => '94105'
+    ],
+    'country_code' => 'US'
+    // 'logo' => new SplFileInfo('/path/to/logo.jpg')
+    // 'logo' => '/path/to/logo.jpg'
+];
+
+try {
+    $response = $businessGateway->invoiceTemplateService()->createTemplate($templateData);
+
+    if ($response->isSuccessful()) {
+        $responseData = $response->getDecodeResponse();
+        $createdTemplateId = $responseData['data']['id'];
+        echo 'Template created: ' . $createdTemplateId . "\n";
+    } else {
+        echo 'Error creating template: ' . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo 'Exception creating template: ' . $e->getMessage() . "\n";
+}
+
+// ===================================================================
+// CREATE TAX COMPONENT
+// ===================================================================
+
+$taxData = [
+    'name' => 'Sales Tax',
+    'type' => 'percentage',
+    'value' => 8.5,
+    'description' => '8.5% sales tax for California'
+];
+
+try {
+    $response = $businessGateway->invoiceTaxService()->createTax($taxData);
+
+    if ($response->isSuccessful()) {
+        $responseData = $response->getDecodeResponse();
+        $createdTaxId = $responseData['data']['id'];
+        echo 'Tax created: ' . $createdTaxId . "\n";
+    } else {
+        echo 'Error creating tax: ' . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo 'Exception creating tax: ' . $e->getMessage() . "\n";
+}
+
+// ===================================================================
+// CREATE DISCOUNT COMPONENT
+// ===================================================================
+
+$discountData = [
+    'name' => 'Early Payment Discount',
+    'type' => 'percentage',
+    'value' => 10.0,
+    'description' => '10% discount for early payment'
+];
+
+try {
+    $response = $businessGateway->invoiceDiscountService()->createDiscount($discountData);
+
+    if ($response->isSuccessful()) {
+        $responseData = $response->getDecodeResponse();
+        $createdDiscountId = $responseData['data']['id'];
+        echo 'Discount created: ' . $createdDiscountId . "\n";
+    } else {
+        echo 'Error creating discount: ' . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo 'Exception creating discount: ' . $e->getMessage() . "\n";
+}
+
+// ===================================================================
+// CREATE PRODUCT COMPONENT
+// ===================================================================
+
+$productData = [
+    'name' => 'Website Development Package',
+    'sku' => 'WEB-DEV-001',
+    'type' => 'digital',
+    'description' => 'Complete website development with responsive design.',
+    'prices' => [
+        [
+            'price' => 2500.00,
+            'currency' => 'USD'
+        ]
+    ]
+    // 'image' => new SplFileInfo('/path/to/image.jpg')
+    // 'image' => '/path/to/image.jpg'
+];
+
+try {
+    $response = $businessGateway->invoiceProductService()->createProduct($productData);
+
+    if ($response->isSuccessful()) {
+        $responseData = $response->getDecodeResponse();
+        $createdProductId = $responseData['data']['id'];
+        echo 'Product created: ' . $createdProductId . "\n";
+    } else {
+        echo 'Error creating product: ' . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo 'Exception creating product: ' . $e->getMessage() . "\n";
+}
+
+// ===================================================================
+// CREATE INVOICE - Using Created Component IDs
+// ===================================================================
+
+echo "1. Creating invoice (non-embedded)\n";
+echo "-------------------\n";
+
+$createdInvoiceId = null;
+
+if ($createdTemplateId && $createdTaxId && $createdDiscountId && $createdProductId && $createdContactId) {
+    $invoiceDataWithIds = [
+        'invoice_template_id' => $createdTemplateId,
+        'tax_id' => $createdTaxId,
+        'discount_id' => $createdDiscountId,
+        'currency' => 'USD',
+        'summary' => 'Website development project using created components',
+        'number' => 'INV-' . date('Y') . '-' . sprintf('%06d', rand(1, 999999)),
+        'contact_id' => $createdContactId,
+        'due_date' => date('Y-m-d', strtotime('+30 days')),
+        'items' => [
+            [
+                'price' => 2500.00,
+                'product_id' => $createdProductId,
+                'tax_id' => $createdTaxId,
+                'discount_id' => $createdDiscountId,
+                'quantity' => 1
+            ]
+        ]
+    ];
+
+    try {
+        $response = $businessGateway->invoiceService()->createInvoice($invoiceDataWithIds);
+
+        if ($response->isSuccessful()) {
+            $responseData = $response->getDecodeResponse();
+            $createdInvoiceId = $responseData['data']['id'];
+            echo 'Invoice created with component IDs: ' . $createdInvoiceId . "\n";
+        } else {
+            echo 'Error creating invoice: ' . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo 'Exception creating invoice: ' . $e->getMessage() . "\n";
+    }
+} else {
+    echo "Cannot create invoice - missing required components\n";
+}
+
+// ===================================================================
+// CREATE INVOICE - With Embedded Components (Alternative approach)
+// ===================================================================
+
+echo "2. Creating invoice (embedded)\n";
+echo "-------------------\n";
+
+$embeddedInvoiceId = null;
+
+if ($createdContactId) {
+    $invoiceDataWithEmbedded = [
+        'template' => [
+            'name' => 'Embedded Template',
+            'footer' => 'Thank you for choosing our services!',
+            'colors' => [
+                'primary' => '#059669',
+                'secondary' => '#f0fdf4'
+            ],
+            'localized_address' => [
+                'address_line1' => '456 Commerce St',
+                'locality' => 'Los Angeles',
+                'administrative_area' => 'CA',
+                'postal_code' => '90210'
+            ],
+            'country_code' => 'US'
+            // 'logo' => new SplFileInfo('/path/to/embedded-logo.jpg')
+            // 'logo' => '/path/to/embedded-logo.jpg'
+        ],
+        'tax' => [
+            'name' => 'State Sales Tax',
+            'type' => 'percentage',
+            'value' => 7.25,
+            'description' => '7.25% California state sales tax'
+        ],
+        'discount' => [
+            'name' => 'First Time Customer Discount',
+            'type' => 'flat',
+            'value' => 100.00,
+            'currency' => 'USD',
+            'description' => '$100 discount for first-time customers'
+        ],
+        'currency' => 'USD',
+        'summary' => 'Website development with embedded components',
+        'number' => 'INV-EMB-' . date('Y') . '-' . sprintf('%06d', rand(1, 999999)),
+        'contact_id' => $createdContactId,
+        'due_date' => date('Y-m-d', strtotime('+45 days')),
+        'items' => [
+            [
+                'price' => 3000.00,
+                'product' => [
+                    'sku' => 'WEB-DEV-PREMIUM',
+                    'type' => 'digital',
+                    'name' => 'Premium Website Development',
+                    'description' => 'Premium website development with advanced features',
+                    // 'image' => new SplFileInfo('/path/to/product-image.jpg')
+                    // 'image' => '/path/to/product-image.jpg'
+                    'prices' => [
+                        [
+                            'price' => 3000.00,
+                            'currency' => 'USD'
+                        ]
+                    ]
+                ],
+                'tax' => [
+                    'name' => 'Service Tax',
+                    'type' => 'percentage',
+                    'value' => 5.0,
+                    'description' => '5% service tax'
+                ],
+                'discount' => [
+                    'name' => 'Bulk Service Discount',
+                    'type' => 'percentage',
+                    'value' => 5.0,
+                    'description' => '5% discount for premium services'
+                ],
+                'quantity' => 1
+            ]
+        ]
+    ];
+
+    try {
+        $response = $businessGateway->invoiceService()->createInvoice($invoiceDataWithEmbedded);
+
+        if ($response->isSuccessful()) {
+            $responseData = $response->getDecodeResponse();
+            $embeddedInvoiceId = $responseData['data']['id'];
+            echo 'Invoice created with embedded components: ' . $embeddedInvoiceId . "\n";
+        } else {
+            echo 'Error creating embedded invoice: ' . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo 'Exception creating embedded invoice: ' . $e->getMessage() . "\n";
+    }
+}
+
+// ===================================================================
+// UPDATE INVOICE - Use Created Invoice ID
+// ===================================================================
+
+echo "3. Updating invoice\n";
+echo "-------------------\n";
+
+if ($createdInvoiceId) {
+    $updateData = [
+        'summary' => 'Updated website development project',
+        'items' => [
+            [
+                'price' => 2750.00, // Updated price
+                'product_id' => $createdProductId,
+                'tax_id' => $createdTaxId,
+                'discount_id' => $createdDiscountId,
+                'quantity' => 1
+            ]
+        ]
+    ];
+
+    try {
+        $response = $businessGateway->invoiceService()->updateInvoice($createdInvoiceId, $updateData);
+
+        if ($response->isSuccessful()) {
+            echo 'Invoice updated successfully: ' . $createdInvoiceId . "\n";
+        } else {
+            echo 'Error updating invoice: ' . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo 'Exception updating invoice: ' . $e->getMessage() . "\n";
+    }
+}
+
+// ===================================================================
+// LIST INVOICES
+// ===================================================================
+
+echo "4. Listing invoices\n";
+echo "-------------------\n";
+
+$filters = [
+    'per_page' => 20,
+    'page' => 1
+    'status' => 'draft',
+    'include' => 'items,items.product.prices'
+];
+
+try {
+    $response = $businessGateway->invoiceService()->listInvoices($filters);
+
+    if ($response->isSuccessful()) {
+        $responseData = $response->getDecodeResponse();
+        $invoices = $responseData['data']['data'];
+        echo 'Found ' . count($invoices) . ' draft invoices' . "\n";
+
+        foreach ($invoices as $invoice) {
+            echo '  - Invoice ID: ' . $invoice['id'] . ' - Status: ' . $invoice['status'] . "\n";
+        }
+    } else {
+        echo 'Error listing invoices: ' . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo 'Exception listing invoices: ' . $e->getMessage() . "\n";
+}
+
+// ===================================================================
+// GET INVOICE DETAILS - Use Created Invoice ID
+// ===================================================================
+
+echo "5. Getting invoice details\n";
+echo "-------------------\n";
+
+if ($createdInvoiceId) {
+    try {
+        $response = $businessGateway->invoiceService()->getInvoice($createdInvoiceId);
+
+        if ($response->isSuccessful()) {
+            $responseData = $response->getDecodeResponse();
+            $invoice = $responseData['data'];
+            echo 'Retrieved invoice details:' . "\n";
+            echo '  ID: ' . $invoice['id'] . "\n";
+            echo '  Status: ' . $invoice['status'] . "\n";
+            echo '  Currency: ' . $invoice['currency'] . "\n";
+            echo '  Summary: ' . $invoice['summary'] . "\n";
+        } else {
+            echo 'Error getting invoice details: ' . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo 'Exception getting invoice details: ' . $e->getMessage() . "\n";
+    }
+}
+
+// ===================================================================
+// SEND INVOICE - Use Embedded Invoice ID
+// ===================================================================
+
+echo "6. Sending invoice\n";
+echo "-------------------\n";
+
+if ($embeddedInvoiceId) {
+    $sendParams = [
+        'email' => 'customer@example.com'
+    ];
+
+    try {
+        $response = $businessGateway->invoiceService()->sendInvoice($embeddedInvoiceId, $sendParams);
+
+        if ($response->isSuccessful()) {
+            echo 'Invoice sent successfully to: ' . $sendParams['email'] . ' for invoice: ' . $embeddedInvoiceId . "\n";
+        } else {
+            echo 'Error sending invoice: ' . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo 'Exception sending invoice: ' . $e->getMessage() . "\n";
+    }
+}
+
+// ===================================================================
+// UPDATE INVOICE STATUS - Use Created Invoice ID
+// ===================================================================
+
+echo "7. Updating invoice status\n";
+echo "-------------------\n";
+
+if ($createdInvoiceId) {
+    $statusData = [
+        'status' => 'void'
+    ];
+
+    try {
+        $response = $businessGateway->invoiceService()->updateInvoiceStatus($createdInvoiceId, $statusData);
+
+        if ($response->isSuccessful()) {
+            echo 'Invoice status updated to: ' . $statusData['status'] . ' for invoice: ' . $createdInvoiceId . "\n";
+        } else {
+            echo 'Error updating invoice status: ' . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo 'Exception updating invoice status: ' . $e->getMessage() . "\n";
+    }
+}
+
+// ===================================================================
+// DOWNLOAD INVOICE PDF - Use Created Invoice ID
+// ===================================================================
+
+echo "8. Downloading invoice PDF\n";
+echo "-------------------\n";
+
+if ($createdInvoiceId) {
+    try {
+        $response = $businessGateway->invoiceService()->downloadInvoicePdf($createdInvoiceId);
+
+        if ($response->isSuccessful()) {
+            $pdfContent = $response->getRawResponse();
+            echo 'PDF downloaded successfully for: ' . $createdInvoiceId . "\n";
+            echo 'PDF size: ' . strlen($pdfContent) . ' bytes' . "\n";
+
+            // Save to file if needed
+            // file_put_contents('invoice_' . $createdInvoiceId . '.pdf', $pdfContent);
+        } else {
+            echo 'Error downloading PDF: ' . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo 'Exception downloading PDF: ' . $e->getMessage() . "\n";
+    }
+}
\ No newline at end of file
diff --git a/code-samples/business/e-invoice/product.php b/code-samples/business/e-invoice/product.php
new file mode 100644
index 0000000..f60028e
--- /dev/null
+++ b/code-samples/business/e-invoice/product.php
@@ -0,0 +1,174 @@
+<?php
+
+require_once('../../../lib/autoload.php');
+
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => '<your-public-key>',
+    'privateKey' => '<your-private-key>',
+]);
+
+echo "FasterPay Invoice Product API Examples\n";
+echo "=========================================\n\n";
+
+// Example 1: Create product
+echo "1. Creating product\n";
+echo "-------------------\n";
+
+$createData = [
+    'name' => 'Website Development Package',
+    'sku' => 'WEB-DEV-001',
+    'type' => 'digital',
+    'description' => 'Complete website development with modern responsive design.',
+    'prices' => [
+        [
+            'price' => 2500.00,
+            'currency' => 'USD'
+        ]
+    ]
+    // 'image' => '/path/to/product-image.jpg' // Uncomment for image upload (file path)
+    // 'image' => new SplFileInfo('/path/to/product-image.jpg') // Or use SplFileInfo object
+];
+
+try {
+    $response = $businessGateway->invoiceProductService()->createProduct($createData);
+
+    if ($response->isSuccessful()) {
+        echo "Product created successfully\n";
+        $data = $response->getDecodeResponse();
+        $productId = $data['data']['id'] ?: 'PD-' . time();
+        echo "  Product ID: $productId\n";
+        echo "  Name: {$createData['name']}\n";
+        echo "  Type: {$createData['type']}\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 2: Get product details
+echo "2. Getting product details\n";
+echo "--------------------------\n";
+
+try {
+    $response = $businessGateway->invoiceProductService()->getProduct($productId);
+
+    if ($response->isSuccessful()) {
+        echo "Product details retrieved\n";
+        $data = $response->getDecodeResponse();
+        $product = $data['data'] ?: [];
+
+        echo "  ID: " . ($product['id'] ?: $productId) . "\n";
+        echo "  SKU: " . ($product['sku'] ?: 'N/A') . "\n";
+        echo "  Name: " . ($product['name'] ?: 'N/A') . "\n";
+        echo "  Type: " . ($product['type'] ?: 'N/A') . "\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 3: Update product
+echo "3. Updating product\n";
+echo "-------------------\n";
+
+$updateData = [
+    'name' => 'Website Development Package - Premium',
+    'description' => 'Premium website development with enhanced features.',
+    'prices' => [
+        [
+            'price' => 3500.00,
+            'currency' => 'USD'
+        ]
+    ]
+    // 'image' => '/path/to/updated-image.jpg' // Uncomment for image upload (file path)
+    // 'image' => new SplFileInfo('/path/to/updated-image.jpg') // Or use SplFileInfo object
+];
+
+try {
+    $response = $businessGateway->invoiceProductService()->updateProduct($productId, $updateData);
+
+    if ($response->isSuccessful()) {
+        echo "Product updated successfully\n";
+        echo "  Updated name and pricing\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 4: List products
+echo "4. Listing products\n";
+echo "-------------------\n";
+
+try {
+    $response = $businessGateway->invoiceProductService()->listProducts([
+        'per_page' => 20,
+        'page' => 1
+    ]);
+
+    if ($response->isSuccessful()) {
+        echo "Products retrieved successfully\n";
+        $data = $response->getDecodeResponse();
+        $products = $data['data']['data'] ?: [];
+        echo "  Found " . count($products) . " products\n";
+
+        foreach ($products as $product) {
+            $id = $product['id'] ?: 'Unknown';
+            $name = $product['name'] ?: 'Unnamed';
+            echo "    - $name ($id)\n";
+        }
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 5: Delete product price
+echo "5. Deleting product price\n";
+echo "-------------------------\n";
+
+try {
+    $response = $businessGateway->invoiceProductService()->deleteProductPrice($productId, 'USD');
+
+    if ($response->isSuccessful()) {
+        echo "Product price deleted successfully\n";
+        echo "  Deleted USD price for Product ID: $productId\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 6: Delete product
+echo "6. Deleting product\n";
+echo "-------------------\n";
+
+try {
+    $response = $businessGateway->invoiceProductService()->deleteProduct($productId);
+
+    if ($response->isSuccessful()) {
+        echo "Product deleted successfully\n";
+        echo "  Deleted Product ID: $productId\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\nInvoice Product API examples completed!\n";
\ No newline at end of file
diff --git a/code-samples/business/e-invoice/tax.php b/code-samples/business/e-invoice/tax.php
new file mode 100644
index 0000000..d2bf246
--- /dev/null
+++ b/code-samples/business/e-invoice/tax.php
@@ -0,0 +1,196 @@
+<?php
+
+require_once('../../../lib/autoload.php');
+
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => '<your-public-key>',
+    'privateKey' => '<your-private-key>',
+]);
+
+echo "FasterPay Invoice Tax API Examples\n";
+echo "===================================\n\n";
+
+// Example 1: Create a tax
+echo "1. Creating a tax\n";
+echo "----------------------------------\n";
+
+$taxData = [
+    'name' => 'Sales Tax',
+    'type' => 'percentage',
+    'value' => 8.5,
+    'description' => '8.5% sales tax for California'
+];
+
+try {
+    $taxResponse = $businessGateway->invoiceTaxService()->createTax($taxData);
+
+    if ($taxResponse->isSuccessful()) {
+        echo "Tax created successfully\n";
+        $responseData = $taxResponse->getDecodeResponse();
+        $taxId = isset($responseData['data']['id']) ? $responseData['data']['id'] : 'TX-' . time();
+        echo "  Tax ID: " . $taxId . "\n";
+        echo "  Name: " . $taxData['name'] . "\n";
+        echo "  Type: " . $taxData['type'] . "\n";
+        echo "  Rate: " . $taxData['value'] . "%\n";
+        echo "  Description: " . $taxData['description'] . "\n";
+    } else {
+        echo "Error: " . $taxResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 2: Get tax details
+echo "2. Getting tax details\n";
+echo "----------------------\n";
+
+$taxId = isset($taxId) ? $taxId : 'TX-' . time();
+
+try {
+    $detailsResponse = $businessGateway->invoiceTaxService()->getTax($taxId);
+
+    if ($detailsResponse->isSuccessful()) {
+        echo "Tax details retrieved\n";
+        $details = $detailsResponse->getDecodeResponse();
+        $tax = isset($details['data']) ? $details['data'] : [];
+
+        echo "  ID: " . (isset($tax['id']) ? $tax['id'] : $taxId) . "\n";
+        echo "  Name: " . (isset($tax['name']) ? $tax['name'] : 'N/A') . "\n";
+        echo "  Type: " . (isset($tax['type']) ? $tax['type'] : 'N/A') . "\n";
+        echo "  Value: " . (isset($tax['value']) ? $tax['value'] : '0') . "\n";
+        echo "  Currency: " . (isset($tax['currency']) ? $tax['currency'] : 'N/A') . "\n";
+        echo "  Description: " . (isset($tax['description']) ? $tax['description'] : 'N/A') . "\n";
+    } else {
+        echo "Error: " . $detailsResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 3: Update tax
+echo "3. Updating tax\n";
+echo "---------------\n";
+
+$updateData = [
+    'name' => 'Updated Sales Tax',
+    'value' => 9.0,
+    'description' => 'Updated 9% sales tax rate'
+];
+
+try {
+    $updateResponse = $businessGateway->invoiceTaxService()->updateTax($taxId, $updateData);
+
+    if ($updateResponse->isSuccessful()) {
+        echo "Tax updated successfully\n";
+        echo "  Updated rate to: " . $updateData['value'] . "%\n";
+        echo "  Updated description\n";
+    } else {
+        echo "Error: " . $updateResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 4: List all taxes
+echo "4. Listing all taxes\n";
+echo "--------------------\n";
+
+$listFilters = [
+    'page' => 1,
+    'per_page' => 10
+];
+
+try {
+    $listResponse = $businessGateway->invoiceTaxService()->listTaxes($listFilters);
+
+    if ($listResponse->isSuccessful()) {
+        echo "Tax list retrieved\n";
+        $listData = $listResponse->getDecodeResponse();
+        $taxes = isset($listData['data']['data']) ? $listData['data']['data'] : [];
+
+        echo "  Found " . count($taxes) . " taxes\n";
+        foreach ($taxes as $tax) {
+            $id = isset($tax['id']) ? $tax['id'] : 'Unknown';
+            $name = isset($tax['name']) ? $tax['name'] : 'Unnamed';
+            $type = isset($tax['type']) ? $tax['type'] : 'unknown';
+            $value = isset($tax['value']) ? $tax['value'] : '0';
+            echo "    - $name ($type: $value) - ID: $id\n";
+        }
+    } else {
+        echo "Error: " . $listResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 5: Create multiple regional taxes
+echo "5. Creating multiple regional taxes\n";
+echo "-----------------------------------\n";
+
+$regionalTaxes = [
+    [
+        'name' => 'New York State Tax',
+        'type' => 'percentage',
+        'value' => 8.25,
+        'description' => '8.25% sales tax for New York State'
+    ],
+    [
+        'name' => 'Texas State Tax',
+        'type' => 'percentage',
+        'value' => 6.25,
+        'description' => '6.25% sales tax for Texas'
+    ],
+    [
+        'name' => 'European VAT',
+        'type' => 'percentage',
+        'value' => 19.0,
+        'description' => '19% VAT for European Union'
+    ]
+];
+
+foreach ($regionalTaxes as $taxData) {
+    try {
+        $response = $businessGateway->invoiceTaxService()->createTax($taxData);
+
+        if ($response->isSuccessful()) {
+            $responseData = $response->getDecodeResponse();
+            $id = isset($responseData['data']['id']) ? $responseData['data']['id'] : 'TX-REGION-' . time();
+            echo "  Created: {$taxData['name']} ({$taxData['value']}%) - ID: $id\n";
+        } else {
+            echo "  Error creating {$taxData['name']}: " . $response->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo "  Exception creating {$taxData['name']}: " . $e->getMessage() . "\n";
+    }
+}
+
+echo "\n";
+
+// Example 6: Delete tax
+echo "6. Deleting tax\n";
+echo "----------------\n";
+
+$deleteTaxId = isset($vatTaxId) ? $vatTaxId : 'TX-DELETE-' . time();
+
+try {
+    $deleteResponse = $businessGateway->invoiceTaxService()->deleteTax($deleteTaxId);
+
+    if ($deleteResponse->isSuccessful()) {
+        echo "Tax deleted successfully\n";
+        echo "  Deleted Tax ID: " . $deleteTaxId . "\n";
+    } else {
+        echo "Error: " . $deleteResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\nInvoice Tax API examples completed!\n";
\ No newline at end of file
diff --git a/code-samples/business/e-invoice/template.php b/code-samples/business/e-invoice/template.php
new file mode 100644
index 0000000..a7b88e5
--- /dev/null
+++ b/code-samples/business/e-invoice/template.php
@@ -0,0 +1,151 @@
+<?php
+
+require_once('../../../lib/autoload.php');
+
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => '<your-public-key>',
+    'privateKey' => '<your-private-key>',
+]);
+
+echo "FasterPay Invoice Template API Examples\n";
+echo "========================================\n\n";
+
+// Example 1: Create template
+echo "1. Creating template\n";
+echo "--------------------\n";
+
+$templateData = [
+    'name' => 'Professional Template',
+    'footer' => 'Thank you for your business!',
+    'colors' => [
+        'primary' => '#2563eb',
+        'secondary' => '#f8fafc'
+    ],
+    'localized_address' => [
+        'address_line1' => '123 Business Avenue',
+        'locality' => 'San Francisco',
+        'administrative_area' => 'CA',
+        'postal_code' => '94105'
+    ],
+    'country_code' => 'US',
+    // 'logo' => '/path/to/logo.png' // Uncomment for logo upload (file path)
+    // 'logo' => new SplFileInfo('/path/to/logo.png') // Or use SplFileInfo object
+];
+
+try {
+    $response = $businessGateway->invoiceTemplateService()->createTemplate($templateData);
+
+    if ($response->isSuccessful()) {
+        echo "Template created successfully\n";
+        $data = $response->getDecodeResponse();
+        $templateId = $data['data']['id'] ?: 'IT-' . time();
+        echo "  Template ID: $templateId\n";
+        echo "  Name: {$templateData['name']}\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 2: Update template
+echo "2. Updating template\n";
+echo "--------------------\n";
+
+$updateData = [
+    'footer' => 'Updated footer text',
+    'colors' => [
+        'primary' => '#059669',
+        'secondary' => '#ecfdf5'
+    ],
+    // 'logo' => '/path/to/new-logo.png' // Uncomment for logo upload (file path)
+    // 'logo' => new SplFileInfo('/path/to/new-logo.png') // Or use SplFileInfo object
+];
+
+try {
+    $response = $businessGateway->invoiceTemplateService()->updateTemplate($templateId, $updateData);
+
+    if ($response->isSuccessful()) {
+        echo "Template updated successfully\n";
+        echo "  Updated colors and footer\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 3: Get template details
+echo "3. Getting template details\n";
+echo "---------------------------\n";
+
+try {
+    $response = $businessGateway->invoiceTemplateService()->getTemplate($templateId);
+
+    if ($response->isSuccessful()) {
+        echo "Template details retrieved\n";
+        $data = $response->getDecodeResponse();
+        $template = $data['data'] ?: [];
+
+        echo "  ID: " . ($template['id'] ?: $templateId) . "\n";
+        echo "  Name: " . ($template['name'] ?: 'N/A') . "\n";
+        echo "  Country: " . ($template['country_code'] ?: 'N/A') . "\n";
+        echo "  Footer: " . ($template['footer'] ?: 'N/A') . "\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 4: List templates
+echo "4. Listing templates\n";
+echo "--------------------\n";
+
+try {
+    $response = $businessGateway->invoiceTemplateService()->listTemplates(['page' => 1, 'per_page' => 10]);
+
+    if ($response->isSuccessful()) {
+        echo "Templates retrieved successfully\n";
+        $data = $response->getDecodeResponse();
+        $templates = $data['data']['data'] ?: [];
+        echo "  Found " . count($templates) . " templates\n";
+
+        foreach ($templates as $template) {
+            $id = $template['id'] ?: 'Unknown';
+            $name = $template['name'] ?: 'Unnamed';
+            echo "    - $name ($id)\n";
+        }
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 5: Delete template
+echo "5. Deleting template\n";
+echo "--------------------\n";
+
+try {
+    $response = $businessGateway->invoiceTemplateService()->deleteTemplate($templateId);
+
+    if ($response->isSuccessful()) {
+        echo "Template deleted successfully\n";
+        echo "  Deleted Template ID: $templateId\n";
+    } else {
+        echo "Error: " . $response->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\nInvoice Template API examples completed!\n";
\ No newline at end of file
diff --git a/code-samples/business/payout.php b/code-samples/business/payout.php
new file mode 100644
index 0000000..adc383f
--- /dev/null
+++ b/code-samples/business/payout.php
@@ -0,0 +1,128 @@
+<?php
+
+require_once('../../lib/autoload.php');
+
+$businessGateway = new FasterPay\BusinessGateway([
+    'publicKey' => '<your-public-key>',
+    'privateKey' => '<your-private-key>',
+]);
+
+echo "=== FasterPay Mass Payout API Examples ===\n\n";
+
+// Example 1: Create mass payout following API documentation
+echo "1. Creating mass payout\n";
+echo "-----------------------\n";
+
+$massPayoutParams = [
+    'source_currency' => 'USD',
+    'template' => 'wallet',
+    'payouts' => [
+        [
+            'reference_id' => 'payout_001',
+            'amount' => '150.00',
+            'amount_currency' => 'USD',
+            'target_currency' => 'USD',
+            'receiver_full_name' => 'John Doe',
+            'receiver_email' => 'john@example.com',
+            'receiver_type' => 'private'
+        ],
+        [
+            'reference_id' => 'payout_002',
+            'amount' => '75.50',
+            'amount_currency' => 'USD',
+            'target_currency' => 'USD',
+            'receiver_full_name' => 'Jane Smith Corporation',
+            'receiver_email' => 'jane@example.com',
+            'receiver_type' => 'business'
+        ]
+    ]
+];
+
+$createdPayoutIds = [];
+
+try {
+    $massPayoutResponse = $businessGateway->payoutService()->createPayout($massPayoutParams);
+
+    if ($massPayoutResponse->isSuccessful()) {
+        echo "Mass payout created successfully\n";
+        $responseData = $massPayoutResponse->getDecodeResponse();
+
+        // Extract payout IDs from response for further operations
+        if (isset($responseData['data']) && is_array($responseData['data'])) {
+            foreach ($responseData['data'] as $payoutItem) {
+                $createdPayoutIds[] = $payoutItem['id'];
+                echo "Payout ID: " . $payoutItem['id'] . " - Status: " . $payoutItem['status'] . "\n";
+            }
+        }
+    } else {
+        echo "Error: " . $massPayoutResponse->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
+
+echo "\n";
+
+// Example 2: Get payout details using ID from create response
+echo "2. Getting payout details\n";
+echo "-------------------------\n";
+
+if (!empty($createdPayoutIds)) {
+    $payoutId = $createdPayoutIds[0]; // Use first created payout ID
+    echo "Using payout ID from create response: " . $payoutId . "\n";
+
+    try {
+        $payoutDetails = $businessGateway->payoutService()->getPayoutDetails($payoutId);
+
+        if ($payoutDetails->isSuccessful()) {
+            echo "Payout details retrieved successfully\n";
+            $responseData = $payoutDetails->getDecodeResponse();
+
+            if (isset($responseData['data'])) {
+                $data = $responseData['data'];
+                echo "Payout ID: " . $data['id'] . "\n";
+                echo "Status: " . $data['status'] . "\n";
+                echo "Receiver: " . $data['receiver_full_name'] . " (" . $data['receiver_email'] . ")\n";
+                echo "Amount: " . $data['amounts']['target_amount'] . " " . $data['amounts']['target_currency'] . "\n";
+            }
+        } else {
+            echo "Error: " . $payoutDetails->getErrors()->getMessage() . "\n";
+        }
+    } catch (FasterPay\Exception $e) {
+        echo "Exception: " . $e->getMessage() . "\n";
+    }
+} else {
+    echo "No payout ID available from previous create operation\n";
+}
+
+echo "\n";
+
+// Example 3: Get payout list with filters
+echo "3. Getting payout list with filters\n";
+echo "-----------------------------------\n";
+
+$filters = [
+    'per_page' => 20,
+    'page' => 1,
+];
+
+try {
+    $payoutList = $businessGateway->payoutService()->getPayoutList($filters);
+
+    if ($payoutList->isSuccessful()) {
+        echo "Payout list retrieved successfully\n";
+        $responseData = $payoutList->getDecodeResponse();
+
+        if (isset($responseData['data']['data']) && is_array($responseData['data']['data'])) {
+            echo "Found " . count($responseData['data']['data']) . " payouts\n";
+            foreach ($responseData['data']['data'] as $payout) {
+                echo "- " . $payout['id'] . " (" . $payout['status'] . ") - " .
+                    $payout['amounts']['target_amount'] . " " . $payout['amounts']['target_currency'] . "\n";
+            }
+        }
+    } else {
+        echo "Error: " . $payoutList->getErrors()->getMessage() . "\n";
+    }
+} catch (FasterPay\Exception $e) {
+    echo "Exception: " . $e->getMessage() . "\n";
+}
\ No newline at end of file
diff --git a/lib/FasterPay/BusinessGateway.php b/lib/FasterPay/BusinessGateway.php
new file mode 100644
index 0000000..a43f551
--- /dev/null
+++ b/lib/FasterPay/BusinessGateway.php
@@ -0,0 +1,156 @@
+<?php
+
+namespace FasterPay;
+
+use FasterPay\Services\Business\Address;
+use FasterPay\Services\Business\Contact;
+use FasterPay\Services\Business\EInvoice\Discount;
+use FasterPay\Services\Business\EInvoice\Invoice;
+use FasterPay\Services\Business\EInvoice\Product;
+use FasterPay\Services\Business\EInvoice\Tax;
+use FasterPay\Services\Business\EInvoice\Template;
+use FasterPay\Services\Business\Payout;
+use FasterPay\Services\GenericApiService;
+use FasterPay\Services\HttpService;
+use FasterPay\Services\Signature;
+use FasterPay\Services\Pingback;
+
+class BusinessGateway implements GatewayInterface
+{
+    const BUSINESS_API_BASE_URL = 'https://business.fasterpay.com';
+
+    protected $config;
+    protected $http;
+    protected $baseUrl = '';
+
+    public function __construct($config = [])
+    {
+        if (is_array($config)) {
+            $config = new Config($config);
+        }
+
+        $this->config = $config;
+        $this->config->setBaseUrl(self::BUSINESS_API_BASE_URL);
+
+        $header = [
+            'X-ApiKey: ' . $this->config->getPrivateKey(),
+            'Content-Type: application/json'
+        ];
+
+        $this->http = new HttpClient($header);
+    }
+
+    protected function getBaseUrl()
+    {
+        if (!$url = $this->config->getApiBaseUrl()) {
+            $url = $this->baseUrl;
+        }
+
+        return $url . '/';
+    }
+
+    public function getEndPoint($endpoint)
+    {
+        return $this->getBaseUrl() . $endpoint;
+    }
+
+    public function getHttpClient()
+    {
+        return $this->http;
+    }
+
+    public function signature()
+    {
+        return new Signature($this);
+    }
+
+    public function pingback()
+    {
+        return new Pingback($this);
+    }
+
+    /**
+     * Mass Payout Service
+     *
+     * @return Payout
+     */
+    public function payoutService()
+    {
+        return new Payout(new HttpService($this));
+    }
+
+    /**
+     * Address Service
+     *
+     * @return Address
+     */
+    public function addressService()
+    {
+        return new Address(new HttpService($this));
+    }
+
+    /**
+     * Contact Service
+     *
+     * @return Contact
+     */
+    public function contactService()
+    {
+        return new Contact(new HttpService($this));
+    }
+
+    /**
+     * Invoice Service
+     *
+     * @return Invoice
+     */
+    public function invoiceService()
+    {
+        return new Invoice(new HttpService($this));
+    }
+
+    /**
+     * Invoice Template Service
+     *
+     * @return Template
+     */
+    public function invoiceTemplateService()
+    {
+        return new Template(new HttpService($this));
+    }
+
+    /**
+     * Invoice Tax Service
+     *
+     * @return Tax
+     */
+    public function invoiceTaxService()
+    {
+        return new Tax(new HttpService($this));
+    }
+
+    /**
+     * Invoice Discount Service
+     *
+     * @return Discount
+     */
+    public function invoiceDiscountService()
+    {
+        return new Discount(new HttpService($this));
+    }
+
+    /**
+     * Invoice Product Service
+     *
+     * @return Product
+     */
+    public function invoiceProductService()
+    {
+        return new Product(new HttpService($this));
+    }
+
+    public function getConfig()
+    {
+        return $this->config;
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Gateway.php b/lib/FasterPay/Gateway.php
index 54419fe..4387369 100644
--- a/lib/FasterPay/Gateway.php
+++ b/lib/FasterPay/Gateway.php
@@ -10,14 +10,12 @@
 use FasterPay\Services\Signature;
 use FasterPay\Services\Pingback;
 
-class Gateway
+class Gateway implements GatewayInterface
 {
 
     protected $config;
     protected $http;
     protected $baseUrl = '';
-    protected $project;
-    protected $extraParams = [];
 
     public function __construct($config = [])
     {
diff --git a/lib/FasterPay/GatewayInterface.php b/lib/FasterPay/GatewayInterface.php
new file mode 100644
index 0000000..e52278e
--- /dev/null
+++ b/lib/FasterPay/GatewayInterface.php
@@ -0,0 +1,14 @@
+<?php
+
+namespace FasterPay;
+
+interface GatewayInterface
+{
+    public function getEndPoint($endpoint);
+
+    public function getHttpClient();
+
+    public function signature();
+
+    public function pingback();
+}
\ No newline at end of file
diff --git a/lib/FasterPay/HttpClient.php b/lib/FasterPay/HttpClient.php
index 8eebe4d..7a2ed46 100644
--- a/lib/FasterPay/HttpClient.php
+++ b/lib/FasterPay/HttpClient.php
@@ -35,11 +35,26 @@ public function get($endpoint, array $params = [], array $headers = [])
 
     public function post($endpoint, array $params = [], array $headers = [])
     {
+        $testParams = $params;
+        $files = $this->extractFiles($testParams);
+
+        if (!empty($files)) {
+            return $this->postMultipart($endpoint, $params, $headers);
+        }
+
         return $this->call($endpoint, $params, 'POST', $headers);
     }
 
     public function put($endpoint, array $params = [], array $headers = [])
     {
+        $testParams = $params;
+        $files = $this->extractFiles($testParams);
+
+        if (!empty($files)) {
+            $params['_method'] = 'PUT';
+            return $this->postMultipart($endpoint, $params, $headers);
+        }
+
         return $this->call($endpoint, $params, 'PUT', $headers);
     }
 
@@ -48,6 +63,112 @@ public function delete($endpoint, array $params = [], array $headers = [])
         return $this->call($endpoint, $params, 'DELETE', $headers);
     }
 
+    public function postMultipart($endpoint, array $params = [], array $headers = [])
+    {
+        $ch = $this->init();
+
+        $header = array_merge($this->header, $headers);
+
+        $header = array_filter($header, function($h) {
+            return stripos($h, 'Content-Type:') !== 0;
+        });
+
+        curl_setopt($ch, CURLOPT_HTTPHEADER, $header);
+        curl_setopt($ch, CURLOPT_POST, true);
+        curl_setopt($ch, CURLOPT_URL, $endpoint);
+
+        $files = $this->extractFiles($params);
+        $postData = [];
+
+        $this->buildPostData($params, $postData, '');
+
+        foreach ($files as $fieldName => $fileValue) {
+            if (is_object($fileValue)) {
+                if ($fileValue instanceof \SplFileInfo) {
+                    // Convert SplFileInfo to file path for HTTP compatibility
+                    $filePath = $fileValue->getPathname();
+                    if (class_exists('CURLFile')) {
+                        $postData[$fieldName] = new \CURLFile($filePath);
+                    } else {
+                        $postData[$fieldName] = '@' . $filePath;
+                    }
+                } else {
+                    // Handle other file objects (CURLFile, etc.)
+                    $postData[$fieldName] = $fileValue;
+                }
+            } elseif (is_string($fileValue) && file_exists($fileValue)) {
+                if (class_exists('CURLFile')) {
+                    $postData[$fieldName] = new \CURLFile($fileValue);
+                } else {
+                    $postData[$fieldName] = '@' . $fileValue;
+                }
+            }
+        }
+
+        curl_setopt($ch, CURLOPT_POSTFIELDS, $postData);
+
+        $response = curl_exec($ch);
+        $info = curl_getinfo($ch);
+        curl_close($ch);
+
+        return [
+            'response' => $response,
+            'httpCode' => $info['http_code']
+        ];
+    }
+
+    private function buildPostData(array $data, array &$postData, $prefix)
+    {
+        foreach ($data as $key => $value) {
+            $currentKey = $prefix ? $prefix . '[' . $key . ']' : $key;
+
+            if (is_array($value)) {
+                $this->buildPostData($value, $postData, $currentKey);
+            } else {
+                $postData[$currentKey] = $value;
+            }
+        }
+    }
+
+    private function extractFiles(array &$params)
+    {
+        $files = [];
+        $this->extractFilesRecursive($params, $files, '');
+        return $files;
+    }
+
+    private function extractFilesRecursive(array &$params, array &$files, $prefix)
+    {
+        foreach ($params as $key => $value) {
+            $currentKey = $prefix ? $prefix . '[' . $key . ']' : $key;
+
+            if (is_array($value)) {
+                $this->extractFilesRecursive($params[$key], $files, $currentKey);
+            } elseif ($this->isFileObject($value)) {
+                $files[$currentKey] = $value;
+                unset($params[$key]);
+            }
+        }
+    }
+
+    private function isFileObject($value)
+    {
+        if (is_object($value)) {
+            return $value instanceof \CURLFile ||
+                (class_exists('SplFileInfo') && $value instanceof \SplFileInfo) ||
+                (class_exists('finfo') && method_exists($value, 'getPathname')) ||
+                method_exists($value, '__toString');
+        }
+
+        if (is_string($value) && !empty($value)) {
+            if (filter_var($value, FILTER_VALIDATE_URL)) {
+                return false;
+            }
+            return file_exists($value);
+        }
+
+        return false;
+    }
 
     private function call($endpoint, array $params = [], $method, array $headers = [])
     {
@@ -58,20 +179,23 @@ private function call($endpoint, array $params = [], $method, array $headers = [
 
         switch (strtoupper($method)) {
             case 'POST':
+                curl_setopt($ch, CURLOPT_POST, true);
                 if (!empty($params)) {
                     curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($params));
                 }
+                break;
             case 'PUT':
             case 'DELETE':
                 curl_setopt($ch, CURLOPT_HTTPGET, false);
                 curl_setopt($ch, CURLOPT_CUSTOMREQUEST, $method);
-                curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($params));
+                if (!empty($params)) {
+                    curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($params));
+                }
                 break;
             case 'GET':
                 if (!empty($params)) {
                     $endpoint .= '?' . http_build_query($params);
                 }
-
                 curl_setopt($ch, CURLOPT_POST, false);
                 curl_setopt($ch, CURLOPT_HTTPGET, true);
                 break;
@@ -79,17 +203,13 @@ private function call($endpoint, array $params = [], $method, array $headers = [
 
         curl_setopt($ch, CURLOPT_URL, $endpoint);
 
-
         $response = curl_exec($ch);
-
-
         $info = curl_getinfo($ch);
         curl_close($ch);
 
-        return array(
+        return [
             'response' => $response,
             'httpCode' => $info['http_code']
-        );
+        ];
     }
-
-}
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Response/JsonResponse.php b/lib/FasterPay/Response/JsonResponse.php
new file mode 100644
index 0000000..9b9a258
--- /dev/null
+++ b/lib/FasterPay/Response/JsonResponse.php
@@ -0,0 +1,48 @@
+<?php
+
+namespace FasterPay\Response;
+
+class JsonResponse extends GeneralResponse
+{
+    public function handleResult()
+    {
+        $response = $this->getDecodeResponse();
+        $httpCode = $this->getHttpCode();
+
+        // First check HTTP status
+        if ($httpCode != self::SUCCESS_CODE) {
+            $errorMessage = empty($response['message']) ? self::RESPONSE_ERROR_TEXT : $response['message'];
+            $this->errors = new ResponseError([
+                'message' => $errorMessage,
+                'code' => $httpCode
+            ]);
+            return;
+        }
+
+        // Then check if response was successfully decoded
+        if ($response === null) {
+            $this->errors = new ResponseError([
+                'message' => 'Failed to decode JSON response',
+                'code' => self::DEFAULT_ERROR_CODE
+            ]);
+            return;
+        }
+
+        // Check for success flag in response body
+        if (!empty($response['success'])) {
+            $this->success = true;
+        } else {
+            // Response decoded but success is empty/false/missing
+            $errorMessage = isset($response['message']) ? $response['message'] : 'Request was not successful';
+            $this->errors = new ResponseError([
+                'message' => $errorMessage,
+                'code' => isset($response['code']) ? $response['code'] : self::DEFAULT_ERROR_CODE
+            ]);
+        }
+    }
+
+    public function isSuccessful()
+    {
+        return $this->success === true && empty($this->errors);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Response/PaymentResponse.php b/lib/FasterPay/Response/PaymentResponse.php
index 9f97dbd..90d2030 100644
--- a/lib/FasterPay/Response/PaymentResponse.php
+++ b/lib/FasterPay/Response/PaymentResponse.php
@@ -13,7 +13,10 @@ public function handleResult()
 
         if ($httpCode != self::SUCCESS_CODE) {
             $errorMessage = empty($response['message']) ? self::RESPONSE_ERROR_TEXT : $response['message'];
-            $this->errors = new ResponseError(array('message' => $errorMessage, 'code' => $httpCode));
+            $this->errors = new ResponseError([
+                'message' => $errorMessage,
+                'code' => $httpCode,
+            ]);
         } else {
             $this->success = true;
         }
diff --git a/lib/FasterPay/Response/SubscriptionResponse.php b/lib/FasterPay/Response/SubscriptionResponse.php
index 6d9064b..c67aa31 100644
--- a/lib/FasterPay/Response/SubscriptionResponse.php
+++ b/lib/FasterPay/Response/SubscriptionResponse.php
@@ -14,7 +14,10 @@ public function handleResult()
         } elseif (!empty($response['type']) && $response['type'] == self::RESPONSE_ERROR_TEXT) {
             $errorMessage = empty($response['message']) ? 'Error' : $response['message'];
             $code = empty($response['code']) ? self::DEFAULT_ERROR_CODE : $response['code'];
-            $this->errors = new ResponseError(array('message' => $errorMessage, 'code' => $code));
+            $this->errors = new ResponseError([
+                'message' => $errorMessage,
+                'code' => $code,
+            ]);
         }
     }
 
diff --git a/lib/FasterPay/Services/Business/Address.php b/lib/FasterPay/Services/Business/Address.php
new file mode 100644
index 0000000..138870a
--- /dev/null
+++ b/lib/FasterPay/Services/Business/Address.php
@@ -0,0 +1,36 @@
+<?php
+
+namespace FasterPay\Services\Business;
+
+use FasterPay\Exception;
+use FasterPay\Response\GeneralResponse;
+use FasterPay\Services\GeneralService;
+
+class Address extends GeneralService
+{
+    protected $endpoint = 'api/external/address';
+
+    /**
+     * Get address fields and subdivisions for a country
+     *
+     * @param string $countryCode Country code (ISO 2-letter)
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function getAddressFields($countryCode = '')
+    {
+        if (empty($countryCode)) {
+            throw new Exception('Country code is required');
+        }
+
+        if (strlen($countryCode) !== 2) {
+            throw new Exception('Country code must be 2 characters (ISO 3166-1 alpha-2)');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/fields/' . strtoupper($countryCode));
+
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+
+        return new GeneralResponse($response);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Services/Business/Contact.php b/lib/FasterPay/Services/Business/Contact.php
new file mode 100644
index 0000000..3365cb7
--- /dev/null
+++ b/lib/FasterPay/Services/Business/Contact.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace FasterPay\Services\Business;
+
+use FasterPay\Exception;
+use FasterPay\Response\GeneralResponse;
+use FasterPay\Services\GeneralService;
+
+class Contact extends GeneralService
+{
+    protected $endpoint = 'api/external/contacts';
+
+    public function createContact(array $params = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    public function getContact($contactId = '')
+    {
+        if (empty($contactId)) {
+            throw new Exception('Contact ID is required');
+        }
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $contactId);
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+        return new GeneralResponse($response);
+    }
+
+    public function updateContact($contactId = '', array $params = [])
+    {
+        if (empty($contactId)) {
+            throw new Exception('Contact ID is required');
+        }
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $contactId);
+        $response = $this->httpService->getHttpClient()->put($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    public function deleteContact($contactId = '')
+    {
+        if (empty($contactId)) {
+            throw new Exception('Contact ID is required');
+        }
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $contactId);
+        $response = $this->httpService->getHttpClient()->delete($endpoint);
+        return new GeneralResponse($response);
+    }
+
+    public function listContacts(array $filters = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+        $response = $this->httpService->getHttpClient()->get($endpoint, $filters);
+        return new GeneralResponse($response);
+    }
+}
diff --git a/lib/FasterPay/Services/Business/EInvoice/Discount.php b/lib/FasterPay/Services/Business/EInvoice/Discount.php
new file mode 100644
index 0000000..b9875d4
--- /dev/null
+++ b/lib/FasterPay/Services/Business/EInvoice/Discount.php
@@ -0,0 +1,103 @@
+<?php
+
+namespace FasterPay\Services\Business\EInvoice;
+
+use FasterPay\Exception;
+use FasterPay\Response\GeneralResponse;
+use FasterPay\Services\GeneralService;
+
+class Discount extends GeneralService
+{
+    protected $endpoint = 'api/external/invoices/discounts';
+
+    /**
+     * Create a new invoice discount
+     *
+     * @param array $params Discount parameters
+     * @return GeneralResponse
+     */
+    public function createDiscount(array $params = array())
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Get discount details
+     *
+     * @param string $discountId Discount ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function getDiscount($discountId = '')
+    {
+        if (empty($discountId)) {
+            throw new Exception('Discount ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $discountId);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Update discount
+     *
+     * @param string $discountId Discount ID
+     * @param array $params Updated discount parameters
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function updateDiscount($discountId = '', array $params = array())
+    {
+        if (empty($discountId)) {
+            throw new Exception('Discount ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $discountId);
+
+        $response = $this->httpService->getHttpClient()->put($endpoint, $params);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Delete discount
+     *
+     * @param string $discountId Discount ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function deleteDiscount($discountId = '')
+    {
+        if (empty($discountId)) {
+            throw new Exception('Discount ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $discountId);
+
+        $response = $this->httpService->getHttpClient()->delete($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * List discounts
+     *
+     * @param array $filters Optional filters
+     * @return GeneralResponse
+     */
+    public function listDiscounts(array $filters = array())
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint, $filters);
+
+        return new GeneralResponse($response);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Services/Business/EInvoice/Invoice.php b/lib/FasterPay/Services/Business/EInvoice/Invoice.php
new file mode 100644
index 0000000..50dd3b5
--- /dev/null
+++ b/lib/FasterPay/Services/Business/EInvoice/Invoice.php
@@ -0,0 +1,175 @@
+<?php
+
+namespace FasterPay\Services\Business\EInvoice;
+
+use FasterPay\Exception;
+use FasterPay\Response\GeneralResponse;
+use FasterPay\Services\GeneralService;
+
+/**
+ * FasterPay E-Invoice Service
+ *
+ * Main component service for handling FasterPay e-invoice operations
+ * Follows the same architecture as other business services
+ * Uses PHP 5.4+ latest syntax
+ */
+class Invoice extends GeneralService
+{
+    protected $endpoint = 'api/external/invoices';
+
+    /**
+     * Create a new e-invoice
+     *
+     * @param array $params E-invoice parameters
+     * @return GeneralResponse
+     */
+    public function createInvoice(array $params = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Get e-invoice details
+     *
+     * @param string $invoiceId Invoice ID
+     * @param array $params Optional query parameters (include, etc.)
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function getInvoice($invoiceId = '', array $params = [])
+    {
+        if (empty($invoiceId)) {
+            throw new Exception('Invoice ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $invoiceId);
+        $response = $this->httpService->getHttpClient()->get($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * List invoices with optional filters
+     *
+     * @param array $filters Optional filters
+     * @return GeneralResponse
+     */
+    public function listInvoices(array $filters = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+        $response = $this->httpService->getHttpClient()->get($endpoint, $filters);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Update e-invoice
+     *
+     * @param string $invoiceId Invoice ID
+     * @param array $params Updated invoice parameters
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function updateInvoice($invoiceId = '', array $params = [])
+    {
+        if (empty($invoiceId)) {
+            throw new Exception('Invoice ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $invoiceId);
+        $response = $this->httpService->getHttpClient()->put($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Update invoice status
+     *
+     * @param string $invoiceId Invoice ID
+     * @param array $params Status parameters
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function updateInvoiceStatus($invoiceId = '', array $params = [])
+    {
+        if (empty($invoiceId)) {
+            throw new Exception('Invoice ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $invoiceId . '/status');
+        $response = $this->httpService->getHttpClient()->put($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Preview invoice (get HTML)
+     *
+     * @param string $invoiceId Invoice ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function previewInvoice($invoiceId = '')
+    {
+        if (empty($invoiceId)) {
+            throw new Exception('Invoice ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $invoiceId . '/preview');
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Download invoice PDF
+     *
+     * @param string $invoiceId Invoice ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function downloadInvoicePdf($invoiceId = '')
+    {
+        if (empty($invoiceId)) {
+            throw new Exception('Invoice ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $invoiceId . '/pdf');
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Send invoice to customer
+     *
+     * @param string $invoiceId Invoice ID
+     * @param array $params Send parameters (test, etc.)
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function sendInvoice($invoiceId = '', array $params = [])
+    {
+        if (empty($invoiceId)) {
+            throw new Exception('Invoice ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $invoiceId . '/send');
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Delete e-invoice
+     *
+     * @param string $invoiceId Invoice ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function deleteInvoice($invoiceId = '')
+    {
+        if (empty($invoiceId)) {
+            throw new Exception('Invoice ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $invoiceId);
+        $response = $this->httpService->getHttpClient()->delete($endpoint);
+        return new GeneralResponse($response);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Services/Business/EInvoice/Product.php b/lib/FasterPay/Services/Business/EInvoice/Product.php
new file mode 100644
index 0000000..73192ba
--- /dev/null
+++ b/lib/FasterPay/Services/Business/EInvoice/Product.php
@@ -0,0 +1,130 @@
+<?php
+
+namespace FasterPay\Services\Business\EInvoice;
+
+use FasterPay\Exception;
+use FasterPay\Response\GeneralResponse;
+use FasterPay\Services\GeneralService;
+
+class Product extends GeneralService
+{
+    protected $endpoint = 'api/external/invoices/products';
+
+    /**
+     * Create a new product
+     * Supports multipart/form-data for image uploads
+     *
+     * @param array $params Product parameters
+     * @return GeneralResponse
+     */
+    public function createProduct(array $params = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Get product details
+     *
+     * @param string $productId Product ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function getProduct($productId = '')
+    {
+        if (empty($productId)) {
+            throw new Exception('Product ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $productId);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Update product
+     * Supports multipart/form-data for image uploads
+     *
+     * @param string $productId Product ID
+     * @param array $params Updated product parameters
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function updateProduct($productId = '', array $params = [])
+    {
+        if (empty($productId)) {
+            throw new Exception('Product ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $productId);
+
+        $response = $this->httpService->getHttpClient()->put($endpoint, $params);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Delete product
+     *
+     * @param string $productId Product ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function deleteProduct($productId = '')
+    {
+        if (empty($productId)) {
+            throw new Exception('Product ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $productId);
+
+        $response = $this->httpService->getHttpClient()->delete($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * List products with optional filters
+     *
+     * @param array $filters Optional filters
+     * @return GeneralResponse
+     */
+    public function listProducts(array $filters = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint, $filters);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Delete product price by currency
+     *
+     * @param string $productId Product ID
+     * @param string $currency Currency code (ISO-4217 format)
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function deleteProductPrice($productId = '', $currency = '')
+    {
+        if (empty($productId)) {
+            throw new Exception('Product ID is required');
+        }
+
+        if (empty($currency)) {
+            throw new Exception('Currency is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $productId . '/prices/' . $currency);
+
+        $response = $this->httpService->getHttpClient()->delete($endpoint);
+
+        return new GeneralResponse($response);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Services/Business/EInvoice/Tax.php b/lib/FasterPay/Services/Business/EInvoice/Tax.php
new file mode 100644
index 0000000..5326cb1
--- /dev/null
+++ b/lib/FasterPay/Services/Business/EInvoice/Tax.php
@@ -0,0 +1,103 @@
+<?php
+
+namespace FasterPay\Services\Business\EInvoice;
+
+use FasterPay\Exception;
+use FasterPay\Response\GeneralResponse;
+use FasterPay\Services\GeneralService;
+
+class Tax extends GeneralService
+{
+    protected $endpoint = 'api/external/invoices/taxes';
+
+    /**
+     * Create a new invoice tax
+     *
+     * @param array $params Tax parameters
+     * @return GeneralResponse
+     */
+    public function createTax(array $params = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Get tax details
+     *
+     * @param string $taxId Tax ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function getTax($taxId = '')
+    {
+        if (empty($taxId)) {
+            throw new Exception('Tax ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $taxId);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Update tax
+     *
+     * @param string $taxId Tax ID
+     * @param array $params Updated tax parameters
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function updateTax($taxId = '', array $params = [])
+    {
+        if (empty($taxId)) {
+            throw new Exception('Tax ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $taxId);
+
+        $response = $this->httpService->getHttpClient()->put($endpoint, $params);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Delete tax
+     *
+     * @param string $taxId Tax ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function deleteTax($taxId = '')
+    {
+        if (empty($taxId)) {
+            throw new Exception('Tax ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $taxId);
+
+        $response = $this->httpService->getHttpClient()->delete($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * List taxes
+     *
+     * @param array $filters Optional filters
+     * @return GeneralResponse
+     */
+    public function listTaxes(array $filters = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint, $filters);
+
+        return new GeneralResponse($response);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Services/Business/EInvoice/Template.php b/lib/FasterPay/Services/Business/EInvoice/Template.php
new file mode 100644
index 0000000..7c1043a
--- /dev/null
+++ b/lib/FasterPay/Services/Business/EInvoice/Template.php
@@ -0,0 +1,98 @@
+<?php
+
+namespace FasterPay\Services\Business\EInvoice;
+
+use FasterPay\Exception;
+use FasterPay\Response\GeneralResponse;
+use FasterPay\Services\GeneralService;
+
+class Template extends GeneralService
+{
+    protected $endpoint = 'api/external/invoices/templates';
+
+    /**
+     * Create a new invoice template
+     *
+     * @param array $params Template parameters (files auto-detected)
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function createTemplate(array $params = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Get template details
+     *
+     * @param string $templateId Template ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function getTemplate($templateId = '')
+    {
+        if (empty($templateId)) {
+            throw new Exception('Template ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $templateId);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Update template
+     *
+     * @param string $templateId Template ID
+     * @param array $params Updated template parameters (files auto-detected)
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function updateTemplate($templateId = '', array $params = [])
+    {
+        if (empty($templateId)) {
+            throw new Exception('Template ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $templateId);
+        $response = $this->httpService->getHttpClient()->put($endpoint, $params);
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * Delete template
+     *
+     * @param string $templateId Template ID
+     * @return GeneralResponse
+     * @throws Exception
+     */
+    public function deleteTemplate($templateId = '')
+    {
+        if (empty($templateId)) {
+            throw new Exception('Template ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $templateId);
+
+        $response = $this->httpService->getHttpClient()->delete($endpoint);
+
+        return new GeneralResponse($response);
+    }
+
+    /**
+     * List templates
+     *
+     * @param array $filters Optional filters
+     * @return GeneralResponse
+     */
+    public function listTemplates(array $filters = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+        $response = $this->httpService->getHttpClient()->get($endpoint, $filters);
+        return new GeneralResponse($response);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Services/Business/Payout.php b/lib/FasterPay/Services/Business/Payout.php
new file mode 100644
index 0000000..ddd8274
--- /dev/null
+++ b/lib/FasterPay/Services/Business/Payout.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace FasterPay\Services\Business;
+
+use FasterPay\Exception;
+use FasterPay\Response\JsonResponse;
+use FasterPay\Services\GeneralService;
+
+class Payout extends GeneralService
+{
+    protected $endpoint = 'api/external/payouts';
+
+    /**
+     * Create a mass payout
+     *
+     * @param array $params Payout parameters
+     * @return JsonResponse
+     */
+    public function createPayout(array $params = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->post($endpoint, $params);
+
+        return new JsonResponse($response);
+    }
+
+    /**
+     * Get payout details
+     *
+     * @param string $payoutId Payout ID
+     * @return JsonResponse
+     * @throws Exception
+     */
+    public function getPayoutDetails($payoutId = '')
+    {
+        if (empty($payoutId)) {
+            throw new Exception('Payout ID is required');
+        }
+
+        $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $payoutId);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint);
+
+        return new JsonResponse($response);
+    }
+
+    /**
+     * Get payout list
+     *
+     * @param array $filters Optional filters
+     * @return JsonResponse
+     */
+    public function getPayoutList(array $filters = [])
+    {
+        $endpoint = $this->httpService->getEndPoint($this->endpoint);
+
+        $response = $this->httpService->getHttpClient()->get($endpoint, $filters);
+
+        return new JsonResponse($response);
+    }
+}
\ No newline at end of file
diff --git a/lib/FasterPay/Services/HttpService.php b/lib/FasterPay/Services/HttpService.php
index 17dcece..65288df 100644
--- a/lib/FasterPay/Services/HttpService.php
+++ b/lib/FasterPay/Services/HttpService.php
@@ -2,15 +2,16 @@
 
 namespace FasterPay\Services;
 
-use FasterPay\Gateway;
+use FasterPay\GatewayInterface;
 
 class HttpService implements HttpServiceInterface
 {
+    /**
+     * @var GatewayInterface
+     */
     protected $client;
-    protected $endpoint;
 
-
-    public function __construct(Gateway $client)
+    public function __construct(GatewayInterface $client)
     {
         $this->client = $client;
     }
@@ -28,7 +29,7 @@ public function getEndPoint($endpoint = '')
     public function __call($function, $params)
     {
         if (method_exists($this, $function)) {
-            return call_user_func_array(array($this, $function), $params);
+            return call_user_func_array([$this, $function], $params);
         }
     }
 }
diff --git a/lib/FasterPay/Services/Payment.php b/lib/FasterPay/Services/Payment.php
index 0f0ef4a..0f2965b 100644
--- a/lib/FasterPay/Services/Payment.php
+++ b/lib/FasterPay/Services/Payment.php
@@ -19,7 +19,7 @@ public function refund($orderId = 0, $amount = 0)
         }
 
         $endpoint = $this->httpService->getEndPoint($this->endpoint . '/' . $orderId . '/refund');
-        $params = array('amount' => $amount);
+        $params = ['amount' => $amount];
 
         $response = $this->httpService->getHttpClient()->post($endpoint, $params);
 
diff --git a/lib/FasterPay/Services/Pingback.php b/lib/FasterPay/Services/Pingback.php
index 34299f5..266d5da 100644
--- a/lib/FasterPay/Services/Pingback.php
+++ b/lib/FasterPay/Services/Pingback.php
@@ -1,7 +1,7 @@
 <?php
 namespace FasterPay\Services;
 
-use FasterPay\Gateway;
+use FasterPay\GatewayInterface;
 
 class Pingback
 {
@@ -9,7 +9,7 @@ class Pingback
 
     private $gateway;
 
-    public function __construct(Gateway $gateway)
+    public function __construct(GatewayInterface $gateway)
     {
         $this->gateway = $gateway;
     }
diff --git a/lib/FasterPay/Services/Signature.php b/lib/FasterPay/Services/Signature.php
index 92eb11d..92732b8 100644
--- a/lib/FasterPay/Services/Signature.php
+++ b/lib/FasterPay/Services/Signature.php
@@ -1,7 +1,7 @@
 <?php
 namespace FasterPay\Services;
 
-use FasterPay\Gateway;
+use FasterPay\GatewayInterface;
 
 class Signature
 {
@@ -13,7 +13,7 @@ class Signature
 
     private $gateway = null;
 
-    public function __construct(Gateway $gateway)
+    public function __construct(GatewayInterface $gateway)
     {
         $this->gateway = $gateway;
     }
diff --git a/lib/autoload.php b/lib/autoload.php
index b9908a1..d7ea526 100644
--- a/lib/autoload.php
+++ b/lib/autoload.php
@@ -7,6 +7,23 @@
     throw new Exception('JSON PHP extension is required');
 }
 
+if (!function_exists('hash_equals')) {
+    function hash_equals($a, $b) {
+        echo 'strlen($a): ' . strlen($a);
+        echo 'strlen($b): ' . strlen($b);
+        if (strlen($a) !== strlen($b)) {
+            return false;
+        }
+        
+        $result = 0;
+        for ($i = 0; $i < strlen($a); $i++) {
+            $result |= ord($a[$i]) ^ ord($b[$i]);
+        }
+        echo $result === 0 ? 'YYEESSS' : 'NONONON';
+        return $result === 0;
+    }
+}
+
 function autoload($className)
 {
     if (strpos($className, 'FasterPay') !== 0) {