I'm running the Sipgate pre-configured installation of Zoiper 3.6.2 on two Windows 10 machines.
On my laptop (with integrated speakers) I have a fully functional installation of Zoiper.
On my main server PC I have fully functional installation of Zoiper, except I'm getting no audio output.
The audio wizard outputs no sound on either the Microsoft Sound Mapper or the selected speaker output device (which is my Smart TV connected via an HDMI cable to my graphics card).
Zoiper can make and receive calls - and judging by the sound output monitor it is receiving audio signals but it's just not outputting them to my speaker device.
As per recommendations I have changed the SIP and RTP ports so that the server PC and the laptop listen on different ports, but I doubt it's anything to do with this.
The only thing I can think of is it's something to do with the specific hardware configuration as the install works fine on Windows 10 on my laptop which operates on the same network as the server PC.