Subject: RE: [Sipping] Q.931 and SIP-T

From: Juan Luis Esteban <[email-masked]>
Date: Tue, 29 Oct 2002 16:13:52 +0100

Hi ranjith,

I was thinking about the widespread deployment of PRI/H.323 gateways, in
which case, H225-Q931 interworking is straightforward.
I agree with some comments in the archive in the sense that apparently it
does not require a huge amount of work to put together an interworking draft
for Q.931 once the MIME types have been defined, and some IE/header mappings
are pretty clear in most cases. The ISUP-SIP draft provides most of the
required mechanisms.

Being PSTN interworking a crucial issue (and also an inhibitor for massive
carrier SIP deployments in favor of H.323), is it not generally thought that
interworking with commonly employed PSTN protocols is needed and demanded by
the market ??.

Is there any progess with this issue at all in the SIP community, or is it
generally accepted/believed that this is a "designer" choice ?

What do the authors of SIP-ISUP mapping think about this ?

-----Mensaje original-----
De: Ranjith Mukundan [mailto:[email-masked]]
Enviado el: martes, 29 de octubre de 2002 15:20
Para: Juan Luis Esteban
CC: [email-masked]'
Asunto: Re: [Sipping] Q.931 and SIP-T

you may want to chk the archive when it was discussed previously - may be
about
an year back. you can chk for msgs before and after this one:
http://www1.ietf.org/mail-archive/working-groups/sipping/current/msg00240.ht
ml

we did have some off-list discussions - it remained inconclusive though...

- ranjith..

Juan Luis Esteban wrote:

> Is there any work in progress regarding Q.931-SIP Interworking ?.
> Since ISUP-SIP interworking has been addressed, is there any reason for
> which QSIG and DSS1 interworking has not been addressed ?.
> I would think that since Q.931 is an asymmetrical protocol, its
interworking
> with SIP is not as straightforward as ISUP. Nevertheless, mapping at the
> message level is still possible. At a first glance, messages such as Call
> proceeding and Connect Ack could be generated locally, it would be
> unnecessary to encapsulate them in SIP. Different behaviours should be
also
> taken into account depending on whether the PRI Gateway is User or
> Network...
>
> In practice, Tier 2 and 3 service providers have been deploying low
density
> PRI gateways where possible due to lower costs than SS7 Gateways, even in
> associated signalling scenarios.
>
> Thanks,
>
> Juan Luis Esteban
> Capcom International
>
> [email-masked]
> Tel.: +34 91 217 00 04
> Fax: +34 91 217 00 19
>
> _______________________________________________
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> This list is for NEW development of the application of SIP
> Use [email-masked] for questions on current sip
> Use [email-masked] for new developments of core SIP

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---

From: Ranjith Mukundan <[email-masked]>
Date: Wed, 30 Oct 2002 21:37:58 +0530

juan,

yes, q.931-sip mapping is a definite requirement for pstn interworking scenarios
- as i can re-collect, that is perhaps how far we got during the last discussion
was well.

in so far as sip-t is concerned, unlike in the case of qsig or dpnss access
types, where  mime objects makes sense, in case of q.931 obviously it does not.

- ranjith..