Out of technical interest I have tried to at least get a proof-of-concept Tor phone which works over WiFi. https://github.com/creichert/phonion

It uses TorChat for messaging and Mumble for VOIP (forced over TCP). At one point I had it working on the Raspberry Pi as well. It is not trivial to build at the moment.

Though it can successfully make calls, I am not advertising this as secure or anonymous. It is simply an experiment I did out of interest.