Sending SMS in WordPress (Required WP-SMS plugin)

functions.php

<form method="post" action="">
    <label>
        Destination number:
        <input type="text" value="" name="number" required>
    </label>

    <label>
        Text:
        <textarea name="message" required></textarea>
    </label>

    <input type="submit" name="sendsms">
</form>

<?php
if( isset($_POST['sendsms'])) {
    if( is_object($sms) ) {
        global $sms;
        $sms->to = array($_POST['number']);
        $sms->msg = $_POST['message'];
        $result = $sms->SendSMS();

        if($result) {
            echo 'SMS was sent successfully.';
        }
    }
}
?>