Read incoming and outgoing text messages using an Android application across different Android SDK versions it's not trivial. If yo don't want to appear as SMS application and your application has to read incoming and outgoing SMSs this is your library.
This Android library offers you two main classes to use to start listening text messages. SMS Radar is implemented in top of an Android service. To start / stop listening text messages use SmsRadar.initializeSmsRadarService(context, listener) with a Context instance and a SmsListener implementation.