sms not working

<?php


$err = "";
$msg = "";
// send sms to subscribed users
if (isset($_POST['send'])) {

    $mobile = $_POST['mobile'];
    $description = $_POST['description'];


    if (isset($mobile)|| isset($description)) {

            // sending sms message to subsribed users
        $sms = sendMessage($mobile, $description);
        if ($sms) {

            $msg = "Message sent";
        }else {
            $err = "Failed to sent message";
        }
    }


    }


     function sendMessage($phone_number,$message){

        $curl = curl_init();

        //encoding sent message using urlencode
        $encoded_message =  urlencode($message);

        $api_key = "86a2b20a184ad90ab56b";
        $sender_id = "wizard";
    $url = "https://api.arispatbulk.com/sendmessage.php?key=86a2b20a184ad90ab56b&message=$encoded_message&senderid=wizard&phone=$phone_number";

    echo $url;

        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);

        $json_response = curl_exec($curl);
        curl_close($curl);

        if ($json_response) {
            return true;
        }else {
            return false;
        }


    }


?>

<!DOCTYPE html>
<html>
<head>
    <title></title>
    <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">

</head>
<body>

            <form class="form-horizontal" method="post">
                <?php

                if (isset($msg)) {
                    echo $msg;
                }

                if (isset($err)) {
                    echo $err;
                }

                ?>
            <div class="box box-info">
                <div class="box-body">

        <div class="form-group">
            <label for="" class="col-sm-3 control-label">Mobile Number</label>
            <div class="col-sm-5">
    <input class="form-control" type="tel" name="mobile" placeholder="Mobile Number" required="required">
            </div>
        </div>


        <div class="form-group">
            <label for="" class="col-sm-3 control-label">Description</label>
            <div class="col-sm-8">
    <textarea class="form-control" name="description" required="required" placeholder="Description" style="height:100px;"></textarea>
            </div>
        </div>

    <div class="form-group">
        <label for="" class="col-sm-3 control-label"></label>
        <div class="col-sm-6">
            <button type="submit" class="btn btn-success" name="send">Send</button>
        </div>
    </div>

                </div>
            </div>
            </form>

            <script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
            <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
            <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>

</body>
</html>