[VOIPSEC] Prevailing trends in securing the SIP signaling plane

[Lewis Adam-CAL022]

Second question for the day, I'd like to understand what the folks on
this list see as the emerging trend(s) in protecting the SIP signaling
plane.  The IETF has defined SIPS, which uses either TLS or DTLS.  My
concern is that most SIP stacks don't' run over TCP, and I'm not
convinced that the industry will rally around DTLS (maybe you folks can
change my mind).  IETF also talks about S/MIME (though I don't know
anybody who takes this seriously) and IPsec.  IPsec is also the
direction the 3GPP standards have taken for IMS (using AKA to
authenticate the user and perform key establishment).  Am I missing
anything obvious?  What are the thoughts on TLS/DTLS vs. IPsec?
 
Tx!
Adam