[Sip] Question regarding draft-dotson-sip-mutual-auth-03

["Nils Ohlmeier" <lists at ohlmeier.org>]

Hello,

after reading the mutual auth draft:

http://tools.ietf.org/id/draft-dotson-sip-mutual-auth-03.txt

I have an open question:
what should the client do if the server send authentication informations
in a Proxy-Authentication-Info header back in a let say 200 response, but
when the client computes response it comes to a different result (e.g.
because man in the middle changed something in the messages)?

In chapter 5 of your draft you are simply referring to RFC3261 for more
details regarding the implementation of the UAC. But I failed to find any
information about the UAC handling of this header in 3261. Even RFC2617
gives no hints, at least I did not found any, what a client should do when
the server authentication fails.
So it is probably not your fault, but still an interesting question I
think. Especially because the client has already send its credentials when
the check of the server authentication fails.

Best regards
  Nils Ohlmeier