The SMS Framework is set of modules that enables interaction
between mobile users and Drupal using SMS. Several popular SMS
gateways are supported and the included API allows developers to
add support for additional gateways. The API also allows other
modules to implement SMS features. Integrates with the following
gateways: Clickatell email gateways - sending sms via email
(through supported carriers) Txtlocal smsgui Twilio Mysmsmantra
Mobivity Lox24 Tropo Vianett Wire2Air Mediaburst Mobile Commons
alfahosting Envaya