public class TelephonyServiceDemo extends Activity
{
    private static final String TAG="TelephonyServiceDemo";
    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);

        TelephonyManager teleMgr = 
(TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
        teleMgr.listen(new MyPhoneStateListener(), 
PhoneStateListener.LISTEN_CALL_STATE);
    }

    class MyPhoneStateListener extends PhoneStateListener
    {

        @Override
        public void onCallStateChanged(int state, String incomingNumber) {
            super.onCallStateChanged(state, incomingNumber);

            switch(state)
            {

                case TelephonyManager.CALL_STATE_IDLE:
                    Log.d(TAG, "call state idle...incoming number is["+
incomingNumber+"]");break;
                case TelephonyManager.CALL_STATE_RINGING:
                    Log.d(TAG, "call state ringing...incoming number is["+
incomingNumber+"]");break;
                case TelephonyManager.CALL_STATE_OFFHOOK:
                    Log.d(TAG, "call state Offhook...incoming number is["+
incomingNumber+"]");break;
                default:
                    Log.d(TAG, "call state ["+state+"]incoming number is["+
incomingNumber+"]");break;
            }
        }
    }
}