RE: [Sip] Strict, Semi-Strict and Loose mode in RPH - not a good fit for ets and wps

["James M. Polk" <[e-mail]>]

comments below

At 12:51 PM 11/8/2004 -0500, Janet P Gunn wrote:
>James said
>---
> > > 2 SIP element ignores a namespace it does not recognize (loose)
>
>To this, remember the ID does not say to "fail" the call, just that
>Request. This is one way to inform the calling UAC to know it included a
>namespace or priority value that was not recognizable (meaning not
>ets.0/1/2/3/4 or wps.0/1/2/3/4).
>
>There is no way to inform the UAC of this issue within the SIP Request
>(with the bad namespace.priority-value) without failing the request.
>Meaning, there can be no preferential treatment without the sending element
>
>being told so. SIP doesn't have a "pass, but this wasn't a good choice"
>provisional response like other protocols.
>
>To the user, they might not notice several SIP Request failures, the person
>
>is merely waiting for the call to be set up (still under a second).
>---
>OK, please educate me.
>
>If it "fails" that request, but doesn't "fail" the call, does that mean
>that the UAC resends the request without the RPH?

yep


>If that is what it means, then, for a call which originates in a SIP/IP
>domain, but goes to the PSTN, it would reach the PSTN gateway with no
>indication that it was entitled to special treatment in the PSTN.
>
>While that is better than failing the call, it still isn't the desired
>behavior.

SIP has no mechanism other than failing the request to indicate something 
was wrong. SIP cannot at this time, allow a message to be processed by a 
SIP element (say a proxy) and have that proxy server send the packet 
towards the UAS *and* send some form of a provisional reply to the UAC 
telling it to correct some aspect of itself in future such messages.


>If there is a way that the SIP element can "fail the request but not the
>call", AND make sure that the appropriate RPH namespace and value (and
>authentication)  get to the PSTN gateway, then it might be OK.

A proxy can replace the field in a header, in this case to a more 
appropriate namespace.value - but I do not believe you will want this to 
happen without authentication of the user at the UAC (which would be in the 
form of a 4XX failure - which you are objecting to.... hmmmm)


>Janet
>
>
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cheers,
James

                                *******************
                 Truth is not to be argued... it is to be presented


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