Jingle is P2P with an optional server middleman for firewalled connections only no? I haven't seen any support for actually hosting a voice server with XMPP, only just allowing clients to figure it out themselves. I'll give it a look either way.
XMPP council (disclaimer: I'm a council member for the current term) asked me to some modifications and to re-propose, which I'm about to do. I couldn't find the time so far (cause I'm working on ton on stuffs), but will go back to it very soon.