The request would typically be done after a 3rd party backend call (as a code is needed). The 3rd Party App will then lose focus as the Scan to Pay app will be launched. This request MUST be done from an Activity.

Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setData(Uri.parse("Scan to to{10 DIGIT CODE}/{CALL BACK URL}"));

*The call back URL MUST be URL encoded.