What are some alternatives?
Twilio - Brings voice and messaging to your web and mobile applications.
Nexmo - Nexmo is a simple two way SMS API with global reach and wholesale rates
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.
Bandwidth - Track your Wi-Fi hotspot usage. Zero configuration required. It just works.
CALLR - CALLR is an extremely helpful app for those who have to deal with call control protocols for their business. You can create a customized call control system that will perform a wide range of functions.
VoxImplant - Voximplant is a software program that allows businesses to automate communications by setting up automatic communication systems in the cloud.