Mike..

You mention that TCP is the optimim initialization for Voip.
Doesn't VOIPo recomment UDP when that question comes up?

I agree that TCP is the fastest communication to set up the call but UDP will get it there almost as fast with less overhead.
If everyone went to TCP for setup, I think the servers might overload.

I think you can run SIP over TCP but then UDP for RTP.

Maybe that's why when you set up your router for port forwarding, the selection offers either or both. At least mine does.