I strongly recommend it to watch this :
Can we delete an SMS in Android before it reaches the inbox?
but becareful about android:priority ,
As of Android 1.6, incoming SMS message broadcasts (android.provider.Telephony.SMS_RECEIVED) are delivered as an "ordered broadcast" — meaning that you can tell the system which components should receive the broadcast first.
If you define an android:priority attribute on your SMS-listening , you will then receive the notification before the native SMS application.