diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..723ef36
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.idea
\ No newline at end of file
diff --git a/composer.json b/composer.json
old mode 100644
new mode 100755
index 0da34e1..6b1af0c
--- a/composer.json
+++ b/composer.json
@@ -13,8 +13,8 @@
     }
   ],
   "require": {
-    "php": ">=7.2",
-    "guzzlehttp/guzzle": "^6.2"
+    "php": ">=7.4",
+    "guzzlehttp/guzzle": "^6.2|^7"
   },
   "require-dev": {
     "phpunit/phpunit": "^6.3"
diff --git a/src/Callback.php b/src/Callback.php
new file mode 100755
index 0000000..4ceaca6
--- /dev/null
+++ b/src/Callback.php
@@ -0,0 +1,47 @@
+<?php
+
+namespace SchGroup\IpsPayment;
+
+class Callback
+{
+    private ?string $success;
+    private ?string $failed;
+    private ?string $callback;
+
+    /**
+     * ShopSettings constructor.
+     * @param string|null $success
+     * @param string|null $failed
+     * @param string|null $callback
+     */
+    public function __construct(string $success = null, string $failed = null, string $callback = null)
+    {
+        $this->success  = $success;
+        $this->failed   = $failed;
+        $this->callback = $callback;
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getSuccess(): ?string
+    {
+        return $this->success;
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getFailed(): ?string
+    {
+        return $this->failed;
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getCallback(): ?string
+    {
+        return $this->callback;
+    }
+}
diff --git a/src/Customer.php b/src/Customer.php
old mode 100644
new mode 100755
index c621535..26ec2d0
--- a/src/Customer.php
+++ b/src/Customer.php
@@ -4,56 +4,55 @@
 
 class Customer
 {
+    private string  $firstName;
+    private string  $name;
+    private ?string $email;
+    private ?string $phone;
+
     /**
-     * @var string
-     */
-    private $customerName;
-    /**
-     * @var string
-     */
-    private $customerEmail;
-    /**
-     * @var string
+     * Customer constructor.
+     * @param string      $firstName
+     * @param string      $name
+     * @param string|null $email
+     * @param string|null $phone
      */
-    private $customerPhone;
+    public function __construct(string $name, string $firstName, ?string $email = null, ?string $phone = null)
+    {
+        $this->firstName = $firstName;
+        $this->name = $name;
+        $this->email = $email;
+        $this->phone = $phone;
+    }
 
     /**
-     * Customer constructor.
-     * @param string $customerName
-     * @param string|null $customerEmail
-     * @param string|null $customerPhone
+     * @return string
      */
-    public function __construct(
-        string $customerName,
-        ?string $customerEmail = null,
-        ?string $customerPhone = null
-    ) {
-        $this->customerName = $customerName;
-        $this->customerEmail = $customerEmail;
-        $this->customerPhone = $customerPhone;
+    public function getFirstName(): string
+    {
+        return $this->firstName;
     }
 
     /**
      * @return string
      */
-    public function getCustomerName(): string
+    public function getName(): string
     {
-        return $this->customerName;
+        return $this->name;
     }
 
     /**
      * @return string
      */
-    public function getCustomerEmail(): ?string
+    public function getEmail(): ?string
     {
-        return $this->customerEmail;
+        return $this->email;
     }
 
     /**
      * @return string
      */
-    public function getCustomerPhone(): ?string
+    public function getPhone(): ?string
     {
-        return $this->customerPhone;
+        return $this->phone;
     }
-}
\ No newline at end of file
+}
diff --git a/src/IpsPayment.php b/src/IpsPayment.php
old mode 100644
new mode 100755
index adfc9cf..2921fd1
--- a/src/IpsPayment.php
+++ b/src/IpsPayment.php
@@ -4,32 +4,89 @@
 
 namespace SchGroup\IpsPayment;
 
-use GuzzleHttp\ClientInterface;
+use Exception;
+use JsonException;
 
 class IpsPayment
 {
+    private const HEADERS = ['Content-Type: application/x-www-form-urlencoded'];
+
     /**
-     * @var ClientInterface
+     * @param Transaction $transaction
+     * @return string
+     * @throws JsonException
+     * @throws Exception
      */
-    private $client;
+    public function buildLink(Transaction $transaction): string
+    {
+        $requestBody = $this->prepareParams($transaction);
+        $requestLink = $transaction->getShopSettings()->getTransitionPath();
+        $response = $this->sendRequest($requestLink, $requestBody);
+
+        $this->prepareResponse($response);
+
+        return $response['DirectLinkIs'];
+    }
 
     /**
-     * IpsPayment constructor.
-     * @param ClientInterface $client
+     * @param Transaction $transaction
+     * @return array
      */
-    public function __construct(ClientInterface $client)
+    private function prepareParams(Transaction $transaction): array
     {
-        $this->client = $client;
+        $paramsToString = implode('!', array_values($transaction->toArray()));
+        $paramsToString .= '!' . $transaction->getShopSettings()->getSecretKey();
+        $paramsToString .= '|' . $transaction->getShopSettings()->getSecretKey();
+
+        return array_merge($transaction->toArray(), [
+            'SHA' => hash('sha512', base64_encode($paramsToString))
+        ]);
     }
 
+    /**
+     * @param string $link
+     * @return array
+     * ```php
+     *  [
+     *      'Code'                     => '200',
+     *      'Method'                   => 'GET",
+     *      'Url_To_Redirect_Customer' => '<url-payment-form-web>',
+     *      'SACS'                     => '<token>',
+     *      'DirectLinkIs'             => '<full-uri-redirect>',
+     *  ]
+     *  [
+     *      'ErrorCode'        => '<error-code>',
+     *      'ErrorDescription' => '<error-description>',
+     *  ]
+     * ```
+     * @throws Exception
+     * @throws JsonException
+     */
+    private function sendRequest(string $link, array $body): array
+    {
+        $ch = curl_init();
+        curl_setopt($ch, CURLOPT_URL, $link . '/');
+        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
+        curl_setopt($ch, CURLOPT_POST, 1);
+        curl_setopt($ch, CURLOPT_POSTFIELDS, http_build_query($body));
+        curl_setopt($ch, CURLOPT_HTTPHEADER, self::HEADERS);
+        $result = curl_exec($ch);
+
+        if (curl_errno($ch)) {
+            throw new Exception('Curl request error: ' . $ch);
+        }
+
+        return json_decode($result, true, 512, JSON_THROW_ON_ERROR);
+    }
 
     /**
-     * @param Transaction $transaction
-     * @return string
+     * @param array $response
+     * @throws Exception
      */
-    public function buildLink(Transaction $transaction): string
+    private function prepareResponse(array $response): void
     {
-        return $transaction->getShopSettings()->getApiHost() .'?'. http_build_query($transaction->toArray());
+        if (!isset($response['Code'])) {
+            throw new Exception('ips request error: ' . $response['ErrorDescription']);
+        }
     }
-    
-}
\ No newline at end of file
+}
diff --git a/src/Order.php b/src/Order.php
old mode 100644
new mode 100755
index d1d9fcf..4ac43e1
--- a/src/Order.php
+++ b/src/Order.php
@@ -4,22 +4,10 @@
 
 class Order
 {
-    /**
-     * @var float
-     */
-    private $amount;
-    /**
-     * @var string
-     */
-    private $subscribePeriod;
-    /**
-     * @var string
-     */
-    private $refOrder;
-    /**
-     * @var string
-     */
-    private $subscribe;
+    private float $amount;
+    private ?string $subscribePeriod;
+    private string $refOrder;
+    private ?string $subscribe;
 
     /**
      * Order constructor.
@@ -33,8 +21,7 @@ public function __construct(
         float $amount,
         ?string $subscribe = null,
         ?string $subscribePeriod = null
-    )
-    {
+    ) {
         $this->refOrder = $refOrder;
         $this->subscribe = $subscribe;
         $this->subscribePeriod = $subscribePeriod;
@@ -72,6 +59,4 @@ public function getSubscribe(): ?string
     {
         return $this->subscribe;
     }
-
-
-}
\ No newline at end of file
+}
diff --git a/src/ShopSettings.php b/src/ShopSettings.php
old mode 100644
new mode 100755
index d522914..e17fbe4
--- a/src/ShopSettings.php
+++ b/src/ShopSettings.php
@@ -4,46 +4,26 @@
 
 class ShopSettings
 {
+    private const TRANSACTION_PATH = 'init_transactions';
 
-    /**
-     * @var string
-     */
-    private $Integrated;
-
-    /**
-     * @var string
-     */
-    private $lang;
-    /**
-     * @var string
-     */
-    private $merchantKey;
-    /**
-     * @var string
-     */
-    private $apiHost;
+    private ?string $lang;
+    private string $merchantKey;
+    private string $apiHost;
+    private string $secretKey;
 
     /**
      * ShopSettings constructor.
-     * @param string $merchantKey
-     * @param string $apiHost
-     * @param string|null $Integrated
+     * @param string      $merchantKey
+     * @param string      $apiHost
+     * @param string      $secretKey
      * @param string|null $lang
      */
-    public function __construct(string $merchantKey, string $apiHost, string $Integrated = "NO", string $lang = null)
+    public function __construct(string $merchantKey, string $apiHost, string $secretKey, string $lang = null)
     {
         $this->merchantKey = $merchantKey;
-        $this->Integrated = $Integrated;
         $this->lang = $lang;
         $this->apiHost = $apiHost;
-    }
-
-    /**
-     * @return string
-     */
-    public function getIntegrated(): string
-    {
-        return $this->Integrated;
+        $this->secretKey = $secretKey;
     }
 
     /**
@@ -69,4 +49,20 @@ public function getApiHost(): string
     {
         return $this->apiHost;
     }
-}
\ No newline at end of file
+
+    /**
+     * @return string
+     */
+    public function getTransitionPath(): string
+    {
+        return $this->apiHost . '/' . self::TRANSACTION_PATH;
+    }
+
+    /**
+     * @return string
+     */
+    public function getSecretKey(): string
+    {
+        return $this->secretKey;
+    }
+}
diff --git a/src/Transaction.php b/src/Transaction.php
old mode 100644
new mode 100755
index 607dc5a..3b93378
--- a/src/Transaction.php
+++ b/src/Transaction.php
@@ -4,34 +4,28 @@
 
 class Transaction
 {
-    /**
-     * @var Customer
-     */
-    private $customer;
-
-    /**
-     * @var Order
-     */
-    private $order;
-    /**
-     * @var ShopSettings
-     */
-    private $shopSettings;
+    private Customer $customer;
+    private Order $order;
+    private ShopSettings $shopSettings;
+    private Callback $callback;
 
     /**
      * Transaction constructor.
      * @param Order $order
      * @param Customer $customer
      * @param ShopSettings $shopSettings
+     * @param Callback $callback
      */
     public function __construct(
         Order $order,
         Customer $customer,
-        ShopSettings $shopSettings
+        ShopSettings $shopSettings,
+        Callback $callback
     ) {
         $this->customer = $customer;
         $this->order = $order;
         $this->shopSettings = $shopSettings;
+        $this->callback = $callback;
     }
 
     /**
@@ -40,17 +34,19 @@ public function __construct(
     public function toArray(): array
     {
         $params = [
-            "MerchantKey"=> $this->shopSettings->getMerchantKey(),
-            "RefOrder" => $this->order->getRefOrder(),
-            "amount" => $this->order->getAmount(),
-            "Customer_Name" => $this->customer->getCustomerName(),
-            "Customer_Email" => $this->customer->getCustomerEmail(),
-            "Customer_Phone" => $this->customer->getCustomerPhone(),
-            "Integrated" => $this->shopSettings->getIntegrated(),
+            'MerchantKey' => $this->shopSettings->getMerchantKey(),
+            'amount'      => (string)$this->order->getAmount(),
+            'RefOrder'    => $this->order->getRefOrder(),
         ];
-        if(!empty($this->shopSettings->getLang())) {
-            $params["lang"] = $this->shopSettings->getLang();
-        }
+
+        $this->customer->getName()      && $params['Customer_Name']      = $this->customer->getName();
+        $this->customer->getFirstName() && $params['Customer_FirstName'] = $this->customer->getFirstName();
+        $this->customer->getEmail()     && $params['Customer_Email']     = (string)$this->customer->getEmail();
+        $this->customer->getPhone()     && $params['Customer_Phone']     = (string)$this->customer->getPhone();
+        $this->shopSettings->getLang()  && $params['lang']               = (string)$this->shopSettings->getLang();
+        $this->callback->getCallback()  && $params['urlIPN']             = (string)$this->callback->getCallback();
+        $this->callback->getSuccess()   && $params['urlOK']              = (string)$this->callback->getSuccess();
+        $this->callback->getFailed()    && $params['urlKO']              = (string)$this->callback->getFailed();
 
         return $params;
     }
@@ -78,4 +74,4 @@ public function getShopSettings(): ShopSettings
     {
         return $this->shopSettings;
     }
-}
\ No newline at end of file
+}