SIPShare: P2P SIP-based filesharing from Earthlink

http://www.corante.com/many/archives/2004/09/15/sipshare_p2p_sipbased_filesharing_from_earthlink.php

"Earthlink has released SIPShare, a proof-of-concept P2P filesharing network that uses Session Initiation Protocol (SIP), a tool originally designed for voice and video communications, to set up file sharing networks."