FrontlineSMS allows you to send and receive text messages over a mobile network.
Browser-based and built to run on Windows, Mac and Linux, FrontlineSMS can send text messages via phone, modem or online SMS aggregator.
Using Frontline SMS, you can deliver announcements, conduct polls and automate replies to incoming SMS. You can also visualise incoming data, helping you to quickly understand the results.
FrontlineSMS integrates with Clickatell and IntelliSMS.
Conducting surveys and polls.
Mobilising for demonstrations.
Visualising voting choices.
Designed for NGO use.
Has good user support.
Some limitations in message send rate when using USB modem (8 per minute).
Technical skills required for some database or connection issues.
http://www.frontlinesms.com/user-resources/ Frontline SMS offers user support through their online forum http://frontlinesms.ning.com, for the most part within 24 hours after you post a question. Premium user support and consulting are also available, although these are paid-for services.
Commercial services such as Clickatell.