How to identify byte[] is Microphone or received from RTP at WaveIn_DataAvailable event

[JudyDai001]

private void mForm_Load(object sender, EventArgs e)
{
var waveFormat = new NAudio.Wave.WaveFormat(8000, 16, 1);

        wavIn = new WaveIn();               
        wavIn.DeviceNumber = 0;
        wavIn.WaveFormat = waveFormat;
        wavIn.DataAvailable += wavIn_DataAvailable;


         wavIn.RecordingStopped += WavIn_RecordingStopped;
         wavIn.BufferMilliseconds = 20;


         BWP = new BufferedWaveProvider(waveFormat);
         BWP.DiscardOnBufferOverflow = true;

         wavOut = new WaveOut();    
         wavOut.DeviceNumber = -1;
         wavOut.DesiredLatency = 100;
         wavOut.Init(BWP);


        playRing = new SoundPlayer();

        voice_link = new Link_Voice(configInfo.voiceLocal, configInfo.PlayLoad);
        voice_link.OpenVoiceLinkEvent += Voice_link_OpenVoiceLinkEvent;
        voice_link.Open();
    }

private void wavIn_DataAvailable(object sender, WaveInEventArgs e)
{

            if (voice_link != null)
            {
                if (c_pbxEp != null)
                {
                    voice_link.AddVoice(e.Buffer, c_pbxEp);  //!!!catch voice from micrphone;send to voipother party
                }
            }
        }          
    }
 private void Voice_link_ReceivedVoiceEvent(IPEndPoint remote, byte[] datas)
    {
        List<byte> ret = new List<byte>();
        for (int i = 0; i < datas.Length; i++)
        {
            short val = LawChange.pcma2pcm(datas[i]);
            byte[] tt = BitConverter.GetBytes(val);
            ret.AddRange(tt);
        }
      
        var dd = ret.ToArray();
        BWP.AddSamples(dd, 0, dd.Length);  //Add voice to speak  //!!          
     
    }

//voip other party: will received self voice again