I’m currently working on just such a project: VoIP over satellite.
Getting VoIP to work over dedicated bandwidth 19.2kbps satellite by itself was the easy part.
I’m now working on trying to allow TCP traffic to share the same link. Finding the right combination of transmission sizes and queuing disciplines is not an easy task.
there are a lot of devices out there that could do voice over I.P without a computer. They look like a modem and go connected betwen the phone and the wall jack.You may have one at each end and the call is almost free( only the cost of the internet access on both ends) or you could have only one on the originating end of the call and paid a company that provides internet telephony (ITSP). That normally runs few cents per minute.
Those devices are programed using the phone and a “cheat sheet”