そんなあなたにはICEがお勧め

WHAT: Tutorial on Interactive Connectivity Establishment (ICE)
(http://www.ietf.org/internet-drafts/draft-ietf-mmusic-ice-11.txt)
WHEN: Tuesday, November 7 1130-1300
WHY: ICE is one of the 'core' SIP specifications (according to the
SIP hitchhikers guide) and seeing some good adoption. It's the
IETF tool for NAT traversal for SIP-based media. However,
it's a complex specification. The tutorial will assume only
basic familiarity with SIP, SDP and NAT, and explain the rest.
Participants will emerge with a high level understanding of
the operation of ICE. The tutorial will be based on the pending -12 version.