在安卓手机上录制电话？

我尝试了一下，并使用以下代码来记录拨出的电话，但它没有。

  @Override
  public void onReceive(Context context, Intent intent) 
  {
          this.context = context;
          if (intent.getAction().equalsIgnoreCase(Intent.ACTION_ANSWER)) 
          {
              try
              {
                  phonenbr = intent.getStringExtra(Intent.EXTRA_PHONE_NUMBER);
                  Log.v("GDHGDHGHDGDHGDHGHDGHDGH", phonenbr);
                  recorder.setAudioSource(MediaRecorder.AudioSource.MIC);
                  recorder.setOutputFormat(MediaRecorder.OutputFormat.THREE_GPP);
                  recorder.setAudioEncoder(MediaRecorder.AudioEncoder.AMR_NB);
                  recorder.setOutputFile(pathname);
                  recorder.prepare();
                  recorder.start();
                  recordstarted = 1;
                  telManager= (TelephonyManager)context.getSystemService(Context.TELEPHONY_SERVICE);
              }
              catch(Exception e)
              {
                  e.printStackTrace();
              }


              final PhoneStateListener phoneListener = new PhoneStateListener()
                {
                    @Override
                     public void onCallStateChanged(final int state, final String incomingNumber)
                        {
                            getTelephonyOverview(telManager);
                        }
                };

           telManager.listen(phoneListener, PhoneStateListener.LISTEN_CALL_STATE);

}

}

           public void getTelephonyOverview(final TelephonyManager telManager)
           {
                   int callState = telManager.getCallState();
                   switch (callState)
                   {
                    case TelephonyManager.CALL_STATE_IDLE:
                    {
                        if (recordstarted==1)
                        {
                            recorder.stop();
                            recordstarted =0;
                        }
                        break;
                    }
                }
           }

请为这个问题提供一些很好的解决方案。