Thank you very much for the answer, Tsetso. I appreciate that.
Just checking on 2 questions that arise:
1. My "device" is an Android phone so the the Zoiper Biz/ Pro versions of Zoiper 3/ 5 that you refer to are actually the Pro/ Gold versions of V. 2.2.x (the current Android app) - not the desktop program(s)?
2. The calls I'm wanting to automatically forward are incoming voice calls on the standard phone network (GSM, CDMA, 3G, 4G). Zoiper Pro/ Gold will take these calls and forward them to the VoIP network? Essentially, I'm looking for the phone to function as a Gateway.