Send SMS by HTTP GET request. Create your own Web application to send SMS.
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URL:
http://e-nautia.com/sms/sms.php

The variables:
l: login
p: password
n: recipient number in international format (+CCXXXXXXXXX where CC is the country code and XXXXXXXXX is the local number)
m: message of 160 characters maximum

The error codes:
1: SMS sent successfully
2: wrong identifiers
3: IP banned due to wrong identifiers. Contact the support.
4: incorrect number
5: insufficient credit. Recharge.
6: internal error. Contact the support.

Basic example of a PHP script:
<?php

$r=@file("http://e-nautia.com/sms/sms.php?l=X&p=Y&n=".urlencode("+CCXXXXXXXXX")."&m=".urlencode("Coucou !"));
echo $r[0];?>