I went to Bob's house to finish setting up his network, now that he got an inexpensive switch. It only took a few minutes to set up and testing the network proved it worked as expected.
I then wanted to try Speak Freely, as there are both Windows and Unix clients available (although the program itself is being discontinued, so grab your copies now). It's a nice program, supporting several popular real-time audio protocols and encryption options, but alas, it was written with a peer-to-peer Internet in mind, not the mess we have now. Which means that Bob's firewall/NAT/DHCP appliance had to forward the ports Speak Freely uses.
So far, it seems to be the best of a whole range of VoIP programs Bob's used (primarily because it is peer-to-peer and doesn't require a third party server to communicate through) but a test with one of the other players wasn't quite conclusive—he had severe echo problems on his end, due to either his audio hardware, audio software, or (my thought since he had to configure his firewall/NAT/DHCP appliance to forward the packets) he was getting the audio packets twice. But if we can get this issued cleared up, I think Bob might settle on using this for audio (it is a nice program).