Question

I want to create a service that will have no user interface and always run in the background – looking for an SMS with a particular substring, and then responding with an SMS of its own (sent programmatically, without user intervention). Does anybody know how to do this?

Answer 1

To expand on Darth Beleg’s answer. It’s not actually possible to do what you’re describing (at least not exactly).

The only way you can detect an incoming SMS, as Darth explains, is to listen for an Intent. The reason why it’s not possible to do exactly what you want is that it’s not possible for a Service to listen for an Intent.

I’d recommend a BroadcastReceiver which listens for the Intent and then starts an IntentService (rather than a Service) and respond accordingly. IntentServices don’t run all of the time – they’re started, do their work then shutdown. A much more efficient way of doing what you’re looking for.