Hi Bob,

Reply inline.

> -----Original Message-----
> From: Bob Penfield [mailto:[email protected]]
> Sent: Wednesday, March 21, 2012 9:26 AM
> To: Brett Tate; Kashif Husain; [email protected]
> Subject: RE: [Sip-implementors] 405 response for UPDATE
> 
> I guess that depends on your interpretation of integral to the usage.

>From a RFC 5057 perspective, my understanding is that it would be the methods 
>required for the usage.

However as always, the UA can decide to terminate the dialog anytime it wants.  
For instance if a UA knows that INFO is important for the specific session, the 
UA can terminate a dialog usage because the other side doesn't support INFO 
even though RFC 5057 indicates that the INFO 405 should only terminate the 
transaction.

> If the UA is using UPDATE which includes SDP to modify the session
> parameters, it is important for that session.

Yep.

> What is the UA supposed to do? It was told that it could 
> use UPDATE, so it did. Is it supposed to try UPDATE and 
> then if that fails use INVITE? 

It can do whatever it wants.  It received a 405 indicating UPDATE no longer 
supported.  Thus if it wants to allow the call to continue and attempt the 
modification/refresh again, it should send re-INVITE.

> Why would UPDATE be OK at the beginning of the 
> session and then not be OK later? 

As far as I know it is mostly just a B2BUA side effect.

> If there were no other transactions that included 
> an Allow header, how is the UA supposed to know that 
> it is not OK now? If that is the case, then the
> Allow header is useless.

It isn't useless; however a 405 is possible.

> It just does not make sense.
> 
> 
> cheers,
> (-:bob
> 
> 
> 
> 
> -----Original Message-----
> From: Brett Tate [mailto:[email protected]]
> Sent: Wednesday, March 21, 2012 8:52 AM
> To: Bob Penfield; Kashif Husain; [email protected]
> Subject: RE: [Sip-implementors] 405 response for UPDATE
> 
> If UPDATE was integral to the INVITE usage, it would have been defined
> within RFC 3261.
> 
> > -----Original Message-----
> > From: Bob Penfield [mailto:[email protected]]
> > Sent: Wednesday, March 21, 2012 8:50 AM
> > To: Brett Tate; Kashif Husain; [email protected]
> > Subject: RE: [Sip-implementors] 405 response for UPDATE
> >
> > Then does that mean the RFC 5057 is incorrect when it says:
> >
> >    (3) 405 Method Not Allowed:
> >
> >        501 Not Implemented:
> >
> >       Either of these responses would be aberrant in our example
> >       scenario since support for the NOTIFY method is required by the
> >       usage.  In this case, the UA knows the condition is
> unrecoverable
> >       and should stop sending NOTIFYs on the usage.  Any refresh
> >       subscriptions should be rejected.  In general, these errors
> will
> >       affect at most the usage.  If the request was not integral to
> the
> >       usage (it used an unknown method, or was an INFO inside an
> INVITE
> >       usage, for example), only the transaction will be affected.
> >
> > Typically UPDATE is integral to the INVITE usage.
> >
> >
> > cheers,
> > (-:bob
> >
> >
> >
> >
> > -----Original Message-----
> > From: [email protected] [mailto:sip-
> > [email protected]] On Behalf Of Brett Tate
> > Sent: Wednesday, March 21, 2012 8:46 AM
> > To: Kashif Husain; [email protected]
> > Subject: Re: [Sip-implementors] 405 response for UPDATE
> >
> > > Is this a valid behavior?
> > > Is it allowed to send 405 in this scenario?
> >
> > Yes; the behavior is valid.  Just because UPDATE was allowed, it
> > doesn't mean that it must continue to be allowed.
> >
> > However, the behavior that you are describing is more prevent with
> > B2BUAs reconnecting dialogs that do and don't support UPDATE.
> >
> >
> > _______________________________________________
> > Sip-implementors mailing list
> > [email protected]
> > https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors

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