Необходимо добавить класс SoapSmsGateWay.class.php:

<?php
/**
* /classes/SoapSmsGateWay.class.php
*/
class SoapSmsGateWay {
public function sendSms($messagesData){
$rawPost = "Input:\r\n";
$rawPost .= file_get_contents('php://input');
$rawPost .= "\r\n---\r\nmessageData:\r\n";
$rawPost .= serialize($messagesData);
file_put_contents("log.txt",$rawPost);
return array("status" => "true");
}
}