Android VOIP application without access to internet

Question

I need to develop the VOIP application between 2 android devices.
As I know there is a SIP protocol used for this purpose but it requires registation to SIP server and a

Answer 1

Of course it is possible! Why you would need the internet? As long as you are both connected to the same network that is fine! Below is the java and xml for a working app.

On start up it will provide you with your own local port, for example "52022".. this is random every time and unfortunately that can't be helped. We then enter the IP address of the other phone and THEIR randomly generated port number and press connect. They do exactly the same and hooray you're connected! This test app obviously requires you to be close by to exchange port numbers, but in my proper app I was easily able to request each port number before connecting. Hope this helps!

public class MainActivity extends Activity {

AudioGroup m_AudioGroup;
AudioStream m_AudioStream;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
      StrictMode.setThreadPolicy(policy);
      try {   
          AudioManager audio =  (AudioManager) getSystemService(Context.AUDIO_SERVICE); 
          audio.setMode(AudioManager.MODE_IN_COMMUNICATION);
          m_AudioGroup = new AudioGroup();
          m_AudioGroup.setMode(AudioGroup.MODE_NORMAL);
          m_AudioStream = new AudioStream(InetAddress.getByAddress(getLocalIPAddress ()));
          int localPort = m_AudioStream.getLocalPort();
          m_AudioStream.setCodec(AudioCodec.PCMU);
          m_AudioStream.setMode(RtpStream.MODE_NORMAL);

          ((TextView)findViewById(R.id.lblLocalPort)).setText(String.valueOf(localPort));

          ((Button) findViewById(R.id.button1)).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                String remoteAddress = ((EditText)findViewById(R.id.editText2)).getText().toString();
                String remotePort = ((EditText)findViewById(R.id.editText1)).getText().toString();

                  try {
                    m_AudioStream.associate(InetAddress.getByName(remoteAddress), Integer.parseInt(remotePort));
                } catch (NumberFormatException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                } catch (UnknownHostException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
                  m_AudioStream.join(m_AudioGroup);
            }
        });

          ((Button) findViewById(R.id.button2)).setOnClickListener(new OnClickListener() {

                @Override
                public void onClick(View v) {
                      m_AudioStream.release();
                }
            });

      } catch (Exception e) {
       Log.e("----------------------", e.toString());
       e.printStackTrace();
      }
}

public static byte[] getLocalIPAddress () {
    byte ip[]=null;
       try {
           for (Enumeration en = NetworkInterface.getNetworkInterfaces(); en.hasMoreElements();) {
               NetworkInterface intf = en.nextElement();
               for (Enumeration enumIpAddr = intf.getInetAddresses(); enumIpAddr.hasMoreElements();) {
                   InetAddress inetAddress = enumIpAddr.nextElement();
                   if (!inetAddress.isLoopbackAddress()) {
                    ip= inetAddress.getAddress();
                   }
               }
           }
       } catch (SocketException ex) {
           Log.i("SocketException ", ex.toString());
       }
       return ip;
    }
}

Layout file:

EDIT: The IP address method stopped working at API 22, use below code:

private byte[] getLocalIPAddress() {   
    byte[] bytes = null;

    try {
        // get the string ip
        WifiManager wm = (WifiManager) getSystemService(WIFI_SERVICE);
        String ip = Formatter.formatIpAddress(wm.getConnectionInfo().getIpAddress());

        // convert to bytes
        InetAddress inetAddress = null;
        try {
            inetAddress = InetAddress.getByName(ip);
        } catch (UnknownHostException e) {
            e.printStackTrace();
        }

        bytes = new byte[0];
        if (inetAddress != null) {
            bytes = inetAddress.getAddress();
        }

    } catch (Exception e) {
        e.printStackTrace();
        Toast.makeText(this, R.string.phone_voip_incompatible, Toast.LENGTH_SHORT).show();
    }

    return bytes;
}