Tropo - Tropo is a cloud API for voice and messaging.
SendSMSnow - SendSMSnow is one of the best services over the internet that lets the users to send free SMS in any part of the world in addition to India.
Melrose Labs SMSC Simulator - SMPP SMSC simulator to test SMS messaging applications.
AFreeSMS - AFreeSMS is a free web-based service that allows you to send unlimited free SMS messages online, no need to register, just type your message and send unlimited SMS to anywhere around the world for free.
Clockwork SMS - Clockwork is an Easy Text Message API. An SMS API for Developers. Build powerful apps and include SMS. Signup is free, Try it now.
FreeSMS8 - FreeSMS8 is one of the best SMS sending websites that allow the Indian phone users to send free SMS to any mobile network operating in India.