A New Authentication Scheme for Session Initiation Protocol
Cheng-Chi Lee, Chu-Chi Yang, Shiow-Yuan Huang
Journal of Digital Information Management, Vol. 7, No. 3, 2009.
DOI: 
Link: http://www.dirf.org/jdim/v7n3a1.asp
Abstract:
The Session Initiation Protocol (SIP) is a signaling protocol that controls communication sessions such as conferencing, telephony, and instant messaging in the   Internet community (RFC2543). Before a user gets to use an SIP service provided by a server, an  authendication process must be finished. However, there are   some security problems with SIP authentication yet to be solved, such as server spoofing, off-line password gussing attacks, and the use of the password table. In   this article, we shall propose a new authentication scheme for SIP that does not need the password table.