private void updateUI() {
    if (getSinchServiceInterface() == null) {
        return; // early
    }

    Call call = getSinchServiceInterface().getCall(mCallId);
    if (call != null) {
        mCallerName.setText(call.getRemoteUserId());
        mCallState.setText(call.getState().toString());
        if (call.getState() == CallState.ESTABLISHED) {
            addVideo();
        }
    }
}
 we also should do it on onServiceConnected ()

@Override
public void onServiceConnected() {
    Call call = getSinchServiceInterface().getCall(mCallId);
    if (call != null) {
        if (!mAddedListener) {
            call.addCallListener(new SinchCallListener());
            mAddedListener = true;
        }
    } else {
        Log.e(TAG, "Started with invalid callId, aborting.");
        finish();
    }

    updateUI();
}