This PHP class allows you to send SMS to almost every country directly from your website. All you need is an account on www.tm4b.com and PHP 5.
Also required is either cURL or allow_url_fopen enabled in php.ini

example

// Include the class
require 'class.swd_SMS.php';

// Create the object. (Parameters are optional if they're set in the class already)
$SMS = new swd_SMS('username', 'password');

// Send SMS. First parameter is the cell phone number with country code. (Without leading 00)
$SMS->send('34123456789', 'The message goes here');

// Let's send another just for fun
$SMS->send('34987654321', 'The message goes here');

// All sent messages are stored in an array.
echo '<pre>' . print_r($SMS->sent_messages, true) . '</pre>';


// Each sent message has a unique message ID, which is in the array above as well. With this we can see the message status any time. Like this:

$status = $SMS->fetch_msg_status('MT0052355965-1');

echo '<pre>' . print_r($status, true) . '</pre>';