[Sip-implementors] About the authentication and authorization in inplementation!!!

[Ford Cheng (Leela)]

Title: About the authentication and authorization in inplementation!!!

Dear All:
   I have one question to consult, in implementation, about the AAA
for SIP . I think in implementation, there is no need to Authenticate
SIP message for each Proxy.
    I think  authentication is needed when SIP message pass through
the first Proxy, how to judge it, I think it can be judged from Via headers,
if there are more Via headers, then there is no need to authenticate?
that is , we should think the following SIP Proxies are trusted with IPSEC.
 
   One example is I were a user with account [EMAIL PROTECTED], I send a SIP message
from the proxy of  Yahoo.com, then yahoo.com requires me for authentication,
the following proxy, no matter what it is, in implementation, I think there is no for
 me need to authenticate
    Could any one give me some sugestion?
    I am looking forwards to getting your reply as soon as possible!
    Best regards!
                              Yours: Ford