<?php

    /** php5-curl and php5-json must be installed **/

    function sendRocketSMS($phone, $message, $sender="SMS-Inform") {
        $curl = curl_init();

        curl_setopt($curl, CURLOPT_URL, 'http://api.rocketsms.by/json/send');
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($curl, CURLOPT_POST, true);
        curl_setopt($curl, CURLOPT_POSTFIELDS, "username=1234567890&password=qwerty&sender=" . $sender . "&phone=" . $phone . "&text=" . $message);

        $result = @json_decode(curl_exec($curl), true);

        if ($result && isset($result['id'])) {
            return "Message has been sent. MessageID=" . $result['id'];
        } elseif ($result && isset($result['error'])) {
            return "Error occurred while sending message. ErrorID=" . $result['error'];
        } else {
            return "Service error";
        }
    }

    echo "<pre>";
    echo sendRocketSMS("375297357355", "hello, rocketsms!");
    echo "</pre>";