Subject: RE: [Sipping] RE: calling number blocking at sip/isup gateway

From: "Peterson, Jon" <[email-masked]>
Date: Wed, 6 Feb 2002 00:20:56 -0600

There has been a lot of misleading talk in this thread that half-suggests
that support for presentation restriction in SIP is necessary if you want to
interwork with the PSTN.  I find it hard to believe that there is any
existing national network which requires that every communications protocol
interworking with the PSTN has a feature by which callers can express that
their preference not to reveal their name and telephone number to those they
call. I know of some legacy protocols that interwork with the PSTN worldwide
today that lack this feature. I also think this would be a very difficult
rule to enforce - if a gateway creates properly formed presentation
indicators, I doubt these would be subjected to any scrutiny. Because I
don't think this is a requirement for PSTN interworking, I do not think it
is an absolute dependency in the SIP-ISUP mapping work. We therefore don't
include any mapping in the SIP-ISUP draft, although we do say that SIP-ISUP
implementations can make use of any general SIP privacy mechanism.

All that said, I feel strongly that we should have a way to implement a
presentation restriction feature in SIP. However, if there isn't a general
presentation restriction feature in SIP, that doesn't in any way prevent us
from interworking with the PSTN. If such a general mechanism were defined,
then by all means we can determine how to to map it to the SS7 presentation
restriction mechanism (easily, no doubt). Note that at least one draft (the
early media mechanism) describes the SIP-ISUP mapping relevant to its own
mechanism - at least partially because we didn't want the SIP-ISUP draft to
have a dependency on SIP extensions defined in other drafts.

I guess that although some people may be happy with the DCS sip-privacy
mechanism, I'm not sure that it really has general applicability. I
currently don't think we need to describe a mapping to this mechanism in the
SIP-ISUP draft.

Jon Peterson
NeuStar, Inc.

> -----Original Message-----
> From: Juha Heinanen [mailto:[email-masked]]
> Sent: Wednesday, January 30, 2002 12:28 AM
> To: Jonathan Rosenberg
> Cc: Tom-PT Taylor; [email-masked]'; [email-masked]
> Subject: Re: [Sipping] RE: calling number blocking at sip/isup gateway
> 
> 
> Jonathan Rosenberg writes:
> 
>  > Well, we have a documented way for that in the privacy 
> spec right now,
>  > which is for the proxy to insert the RPID-Privacy header indicating
>  > calling party, with any kind of privacy, and type of subscriber. 
> 
> yes, and i'm prefectly happy with it.  the problem is that 
> the sip-isup
> i-d doesn't say a word about it and it is that document that 
> the ss7/sip
> gw vendors will read.
> 
> -- juha
> 
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_______________________________________________
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---

From: Juha Heinanen <[email-masked]>
Date: Wed, 6 Feb 2002 11:22:33 +0200

> currently don't think we need to describe a mapping to this mechanism in the

if presentation restricted mapping is not defined in the sip-isup i-d,
then there is no hope for interoperability between uas and sip/isup gws
or between proxies and sip/isup gws.  it would mean that i as the
customer of all this equipment would need to negotiate with each vendor
and try to make them implement the same mapping.  this would be in
practise impossible.  therefore, i would not vote for advancing the
sip/isup i-d before it specifies how restricted number presentation is
handled.  

what comes to the solution, i'm happy with the one proposed by someone
from cisco on this mailing list.

-- juha

---

From: Christer Holmberg <[email-masked]>
Date: Wed, 06 Feb 2002 12:35:45 +0200

Hi,

I think the difficult part is to decide which mechanism to use - then we
can argue in where to describe it...

Regards,

Christer Holmberg
Ericsson Finland