Clockwork provides an easy and inexpensive solution for sending low volumes of text messages, with the capability to handle higher volumes if usage grows. I was able to sign up, integrate it with an existing application, test it and release it for live usage in an afternoon. Our application normally uses email communication, but we were asked to provide an SMS alternative for recipients who don't have email but do have phones with text capability. We haven't been using it for very long so I can't comment on reliability, but on the one occasion I had to contact Clockwork's customer service they were very helpful.