private static final String APP_KEY = "4f0f89ba-9dd6-48ff-969a-4870e85e56db";
private static final String APP_SECRET = "YHdLQQ1uBky//yGHiuvUVw==";
private static final String ENVIRONMENT = "sandbox.sinch.com";

private static final String APP_KEY = "4f0f89ba-9dd6-48ff-969a-4870e85e56db";
private static final String APP_SECRET = "YHdLQQ1uBky//yGHiuvUVw==";
private static final String ENVIRONMENT = "sandbox.sinch.com";

public static final String CALL_ID = "CALL_ID";
static final String TAG = SinchService.class.getSimpleName();

private SinchServiceInterface mSinchServiceInterface = new SinchServiceInterface();
private SinchClient mSinchClient;
private String mUserId;

private StartFailedListener mListener;

@Override
public void onCreate() {
    super.onCreate();
}

@Override
public void onDestroy() {
    if (mSinchClient != null && mSinchClient.isStarted()) {
        mSinchClient.terminate();
    }
    super.onDestroy();
}

private void start(String userName) {
    if (mSinchClient == null) {
        mUserId = userName;
        mSinchClient = Sinch.getSinchClientBuilder().context(getApplicationContext()).userId(userName)
                .applicationKey(APP_KEY)
                .applicationSecret(APP_SECRET)
                .environmentHost(ENVIRONMENT).build();

        mSinchClient.setSupportCalling(true);
        mSinchClient.startListeningOnActiveConnection();

        mSinchClient.addSinchClientListener(new MySinchClientListener());
        mSinchClient.getCallClient().addCallClientListener(new SinchCallClientListener());
        mSinchClient.start();
    }
}

private void stop() {
    if (mSinchClient != null) {
        mSinchClient.terminate();
        mSinchClient = null;
    }
}

private boolean isStarted() {
    return (mSinchClient != null && mSinchClient.isStarted());
}

@Override
public IBinder onBind(Intent intent) {
    return mSinchServiceInterface;
}

public class SinchServiceInterface extends Binder {

    public Call callUserVideo(String userId) {
        return mSinchClient.getCallClient().callUserVideo(userId);
    }

    public String getUserName() {
        return mUserId;
    }

    public boolean isStarted() {
        return SinchService.this.isStarted();
    }

    public void startClient(String userName) {
        start(userName);
    }

    public void stopClient() {
        stop();
    }

    public void setStartListener(StartFailedListener listener) {
        mListener = listener;
    }

    public Call getCall(String callId) {
        return mSinchClient.getCallClient().getCall(callId);
    }

    public VideoController getVideoController() {
        if (!isStarted()) {
            return null;
        }
        return mSinchClient.getVideoController();
    }

    public AudioController getAudioController() {
        if (!isStarted()) {
            return null;
        }
        return mSinchClient.getAudioController();
    }
}

public interface StartFailedListener {

    void onStartFailed(SinchError error);

    void onStarted();
}

private class MySinchClientListener implements SinchClientListener {

    @Override
    public void onClientFailed(SinchClient client, SinchError error) {
        if (mListener != null) {
            mListener.onStartFailed(error);
        }
        mSinchClient.terminate();
        mSinchClient = null;
    }

    @Override
    public void onClientStarted(SinchClient client) {
        Log.d(TAG, "SinchClient started");
        if (mListener != null) {
            mListener.onStarted();
        }
    }

    @Override
    public void onClientStopped(SinchClient client) {
        Log.d(TAG, "SinchClient stopped");
    }

    @Override
    public void onLogMessage(int level, String area, String message) {
        switch (level) {
            case Log.DEBUG:
                Log.d(area, message);
                break;
            case Log.ERROR:
                Log.e(area, message);
                break;
            case Log.INFO:
                Log.i(area, message);
                break;
            case Log.VERBOSE:
                Log.v(area, message);
                break;
            case Log.WARN:
                Log.w(area, message);
                break;
        }
    }

    @Override
    public void onRegistrationCredentialsRequired(SinchClient client,
            ClientRegistration clientRegistration) {
    }
}

private class SinchCallClientListener implements CallClientListener {

    @Override
    public void onIncomingCall(CallClient callClient, Call call) {
        Log.d(TAG, "Incoming call");
        Intent intent = new Intent(SinchService.this, IncomingCallScreenActivity.class);
        intent.putExtra(CALL_ID, call.getCallId());
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        SinchService.this.startActivity(intent);
    }
}