What's difficult

Sending Text (SMS) is quite easy and there are many simple alternatives to do it. But handling incoming SMS is another story. You need a so called MO-SMS application (MO stands for Mobile Originated) like the one sketched on left diagram.

Developing such application require a team skilled in different technologies ranging from SMS messaging to Database, Web services, concurrency, and much more. Once the application is ready you still have to maintain it and keep its server up and running.

This represents money and time. If you are a large organization, money may not be a problem, but time is a key factor for marketing success and waiting weeks for a new service offer can be a serious obstacle.