// 取得电话服务
TelephonyManager telManager = (TelephonyManager) getSystemService(Context.TELEPHONY_SERVICE);
//监听电话的状态
telManager.listen(listener, PhoneStateListener.LISTEN_CALL_STATE);
PhoneStateListener listener = new PhoneStateListener(){ 
 @Override public void onCallStateChanged(int state, String incomingNumber) {
  switch (state){
  case TelephonyManager.CALL_STATE_IDLE: /* 无任何状态时 */
  break;
  case TelephonyManager.CALL_STATE_OFFHOOK: /* 接起电话时 */
  break; 
  case TelephonyManager.CALL_STATE_RINGING: /* 电话进来时 */
  break;
  default:
 break;
  }
 super.onCallStateChanged(state, incomingNumber);
 }
};