Best of luck to the project.

I already planned on using Sip Witch to set up a purely client-server intranet SIP env some time, that it can already do. Mesh support would make it more of a p2p app and less of a server, so I hope for these environments the p2p features can be turned off.

Also would be interesting to hear how GPG hashes of the session key avoids MITM; Zimmerman says they should be read aloud at the start, as the secure way to exchange them.

Oh also,
Skype users can gtfo.