diff --git a/lib/Api.php b/lib/Api.php
index d187a68..962c979 100644
--- a/lib/Api.php
+++ b/lib/Api.php
@@ -277,9 +277,15 @@ public function getPbxRedirection($pbxNumber)
      * @return Statistics
      * @throws ApiException
      */
-    public function getStatistics($start = null, $end = null, $sip = null, $costOnly = null, $type = null, $skip = null,
-                                  $limit = null)
-    {
+    public function getStatistics(
+        $start = null,
+        $end = null,
+        $sip = null,
+        $costOnly = null,
+        $type = null,
+        $skip = null,
+        $limit = null
+    ) {
         $params = [
             'start' => $start,
             'end' => $end,
@@ -306,9 +312,14 @@ public function getStatistics($start = null, $end = null, $sip = null, $costOnly
      * @return PbxStatistics
      * @throws ApiException
      */
-    public function getPbxStatistics($start = null, $end = null, $newFormat = true, $callType = null,
-                                     $skip = null, $limit = null)
-    {
+    public function getPbxStatistics(
+        $start = null,
+        $end = null,
+        $newFormat = true,
+        $callType = null,
+        $skip = null,
+        $limit = null
+    ) {
         $params = [
             'start' => $start,
             'end' => $end,
@@ -463,20 +474,20 @@ public function setPbxRecording($sipId, $status, $email = null, $speechRecogniti
     /**
      * Sending the SMS messages.
      *
-     * @param string number Phone number, where to send the SMS message (several numbers can be specified,
-     * separated by comma);
-     * @param string message Message (standard text limit applies; the text will be separated into several SMS messages,
+     * @param string|array $to Phone number(s), where to send the SMS message (array of numbers can be specified);
+     * @param string $message Message (standard text limit applies; the text will be separated into several SMS messages,
      *  if the limit is exceeded);
-     * @param string caller_id Phone number, from which the SMS messages is sent (can be sent only from list of user's
+     * @param string $callerId Phone number, from which the SMS messages is sent (can be sent only from list of user's
      *  confirmed phone numbers).
      * @return Sms
      * @throws ApiException
      */
     public function sendSms($to, $message, $callerId = null)
     {
+        $to = array_map([self::class, 'filterNumber'], is_array($to) ? $to : [$to]);
         $params = [
-            'number' => self::filterNumber($to),
-            'message' => $message
+            'number' => implode(',', $to),
+            'message' => $message,
         ];
         if ($callerId) {
             $params['caller_id'] = $callerId;
@@ -564,9 +575,12 @@ public function setPbxVoicemailRedirection($pbxNumber, $destination, $always, $g
         if (!filter_var($destination, FILTER_VALIDATE_EMAIL)) {
             throw new \BadFunctionCallException('Wrong email parameter');
         }
-        if (!in_array($greeting, [self::PBX_REDIRECTION_NO_GREETING, self::PBX_REDIRECTION_OWN_GREETING,
-            self::PBX_REDIRECTION_STANDART_GREETING])
-        ) {
+        $allowedRedirections = [
+            self::PBX_REDIRECTION_NO_GREETING,
+            self::PBX_REDIRECTION_OWN_GREETING,
+            self::PBX_REDIRECTION_STANDART_GREETING
+        ];
+        if (!in_array($greeting, $allowedRedirections)) {
             throw new \BadFunctionCallException('Wrong voicemailGreeting parameter');
         }
         $params = [
@@ -577,9 +591,11 @@ public function setPbxVoicemailRedirection($pbxNumber, $destination, $always, $g
             'voicemail_greeting' => $greeting,
         ];
         if ($greeting == self::PBX_REDIRECTION_OWN_GREETING) {
-            if( !$greetingFile || !file_exists($greetingFile) ||
-                !in_array(pathinfo($greetingFile, PATHINFO_EXTENSION), ['wav', 'mp3'])
-            ){
+            if (
+                !$greetingFile
+                || !file_exists($greetingFile)
+                || !in_array(pathinfo($greetingFile, PATHINFO_EXTENSION), ['wav', 'mp3'])
+            ) {
                 throw new \BadFunctionCallException('Greeting file does not exist or has wrong extension.');
             }
             $params['greeting_file'] = curl_file_create($greetingFile);
@@ -806,4 +822,4 @@ protected static function arrayToResultObj($array, $resultClassName)
         }
         return $array;
     }
-}
\ No newline at end of file
+}
diff --git a/lib/Client.php b/lib/Client.php
index 6e6a694..dcf9038 100644
--- a/lib/Client.php
+++ b/lib/Client.php
@@ -1,6 +1,7 @@
 <?php
 
 namespace Zadarma_API;
+
 use Exception;
 
 class Client
@@ -12,7 +13,7 @@ class Client
     private $key;
     private $secret;
     private $httpCode;
-    private $limits = array();
+    private $limits = [];
 
     /**
      * @param $key
@@ -36,28 +37,28 @@ public function __construct($key, $secret, $isSandbox = false)
      * @throws Exception
      *
      */
-    public function call($method, $params = array(), $requestType = 'get', $format = 'json')
+    public function call($method, $params = [], $requestType = 'get', $format = 'json')
     {
         if (!is_array($params)) {
             throw new ApiException('Query params must be an array.');
         }
 
         $type = strtoupper($requestType);
-        if (!in_array($type, array('GET', 'POST', 'PUT', 'DELETE'))) {
+        if (!in_array($type, ['GET', 'POST', 'PUT', 'DELETE'])) {
             $type = 'GET';
         }
         $params['format'] = $format;
 
-        $options = array(
-            CURLOPT_URL            => $this->url . $method,
-            CURLOPT_CUSTOMREQUEST  => $type,
+        $options = [
+            CURLOPT_URL => $this->url . $method,
+            CURLOPT_CUSTOMREQUEST => $type,
             CURLOPT_CONNECTTIMEOUT => 10,
             CURLOPT_RETURNTRANSFER => true,
             CURLOPT_SSL_VERIFYPEER => false,
             CURLOPT_SSL_VERIFYHOST => false,
-            CURLOPT_HEADERFUNCTION => array($this, 'parseHeaders'),
-            CURLOPT_HTTPHEADER     => $this->getAuthHeader($method, $params),
-        );
+            CURLOPT_HEADERFUNCTION => [$this, 'parseHeaders'],
+            CURLOPT_HTTPHEADER => $this->getAuthHeader($method, $params),
+        ];
 
         $ch = curl_init();
 
@@ -65,9 +66,9 @@ public function call($method, $params = array(), $requestType = 'get', $format =
             $options[CURLOPT_URL] = $this->url . $method . '?' . $this->httpBuildQuery($params);
         } else {
             $options[CURLOPT_POST] = true;
-            if(array_filter($params, 'is_object')){
+            if (array_filter($params, 'is_object')) {
                 $options[CURLOPT_POSTFIELDS] = $params;
-            }else{
+            } else {
                 $options[CURLOPT_POSTFIELDS] = $this->httpBuildQuery($params);
             }
         }
@@ -121,12 +122,14 @@ public function encodeSignature($signatureString)
      */
     private function getAuthHeader($method, $params)
     {
-        $params = array_filter($params, function($a){return !is_object($a);});
+        $params = array_filter($params, function ($a) {
+            return !is_object($a);
+        });
         ksort($params);
         $paramsString = $this->httpBuildQuery($params);
         $signature = $this->encodeSignature($method . $paramsString . md5($paramsString));
 
-        return array('Authorization: ' . $this->key . ':' . $signature);
+        return ['Authorization: ' . $this->key . ':' . $signature];
     }
 
     /**
@@ -138,7 +141,7 @@ private function getAuthHeader($method, $params)
     private function parseHeaders($curl, $line)
     {
         if (preg_match('/^X-RateLimit-([a-z]+):\s([0-9]+)/i', $line, $match)) {
-            $this->limits[$match[1]] = (int) $match[2];
+            $this->limits[$match[1]] = (int)$match[2];
         }
 
         return strlen($line);
@@ -151,8 +154,8 @@ private function parseHeaders($curl, $line)
      *
      * @return string
      */
-    private function httpBuildQuery($params = array())
+    private function httpBuildQuery($params = [])
     {
-        return http_build_query($params, null, '&', PHP_QUERY_RFC1738);
+        return http_build_query($params, '', '&', PHP_QUERY_RFC1738);
     }
 }