TelephonyManager Tel; 
MyPhoneStateListener MyListener; 

/* Update the listener, and start it */ 
MyListener = new MyPhoneStateListener(); 
Tel = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE); 
Tel.listen(MyListener, PhoneStateListener.LISTEN_SIGNAL_STRENGTHS); 

private class MyPhoneStateListener extends PhoneStateListener { 
/* 从得到的信号强度,每个tiome供应商有更新 */ 
public void onSignalStrengthsChanged(SignalStrength signalStrength) { 
  super.onSignalStrengthsChanged(signalStrength); 
  Toast.makeText(getApplicationContext(),"Go to Firstdroid!!! GSM Cinr = "+ String.valueOf(signalStrength.getGsmSignalStrength()),Toast.LENGTH_SHORT).show(); 
  } 
};