RE: [Sipping] RE: Mapping ISUP/QSIG causes to SIP response codes

[Adam Roach <adam@dynamicsoft.com>]

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-----Original Message-----
From: Mpierce1@aol.com [mailto:Mpierce1@aol.com]


>[MAP] A problem for ISUP to SIP mapping (and back to ISUP) is that
> several ISUP cause codes (1, 2, and 3) are mapped to 404 which
> then gets mapped back to 1. This would mean that information is
> lost in this case of ISUP-SIP-ISUP interworking. This could prevent
> an originating side from playing an appropriate message. The
> philosophy should be that ISUP/ISDN did a lot of work to define
> the necessary set of cause codes, and all that apply should all
> be carried through SIP unchanged.  

You have touched quite squarely on the motivation for carrying
ISUP bodies in SIP messages. If you're going to press for a
one-to-one mapping between ISUP cause codes and SIP response
codes, you've got a long battle ahead of you. I suggest reading
Don Quixote in preparation for your battle.


> The comments seem to address a number of cases in which there
> would be an ambiguity of whether an error occurred in the
> destination PSTN or in the gateway to the PSTN. Unless there
> is a clear distinction between the two, then there is a serious
> problem. Will it be possible to say, for every response that the
> originating side (UAC or originating proxy) receives, whether
> it was the result of an error in the PSTN or in the gateway?