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

From: Matt Holdrege <[email-masked]>
Date: Fri, 25 Jan 2002 10:08:20 -0800

At 09:07 AM 1/25/2002, Christian Huitema wrote:
>Judging me naïve, Mark Watson wrote:

I would never judge you as naive Christian. :)

>The laws regulating phone services are aimed at telephone service 
>providers, not users.

Correct. So when a telephone call arrives on a SP's network, the SP is 
required to support the local regulation. The language of the law is that 
you are subject if you provide an indiscriminate public telecommunications 
service. If I put my amateur lawyer hat on, that means that if I provide 
SIP services to the public for the purpose of telecommunications, I am 
subject to the requirements of the law. A SIP service is not the same thing 
as Internet service, but I'll argue that if I'm carrying calls between the 
PSTN and a SIP phone, it is a public telecommunications service.

So the result is that if a call comes from the PSTN to a SIP phone and the 
caller requests privacy, then the SIP service provider must honor the 
request. Equally it may apply that if a SIP user calls the PSTN and 
requests privacy, the PSTN must honor it.

Since none of us are lawyers here, it probably does no good to argue this 
further. SP's will do whatever they wish in any case. All we have to do is 
make sure the mechanism is in place to support these privacy requirements. 
In the case of PSTN to SIP calls, we have the option of encapsulating ISUP 
which has the IE for privacy already specified. Or we can map that IE into 
a SIP header. Is there a problem with that?

-Matt           [email-masked]

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From: Dean Willis <[email-masked]>
Date: Fri, 25 Jan 2002 13:57:33 -0600

On Friday 25 January 2002 12:08 pm, Matt Holdrege wrote:
> So the result is that if a call comes from the PSTN to a SIP phone
> and the caller requests privacy, then the SIP service provider must
> honor the request. Equally it may apply that if a SIP user calls the
> PSTN and requests privacy, the PSTN must honor it.

The problem here is that both of these scenarios imply transitive trust 
"into the next world", and personally, my left brain doesn't have 
transitive trust with my right brain so I'm likely to be suspicious of 
the trusting . . .

How about: 

"If a call comes from the PSTN to a SIP phone and the caller requests 
privacy, then the PSTN gateway provider must honor the request.   
Equally it may apply that if a SIP user calls the PSTN and requests 
privacy, the SIP to PSTN gateway must honor it."

This is subtly different from Matt's  wording. It more precisely 
allocates the responsibility.

It's like the old kids game of telling a secret to a friend, then 
saying "don't tell anybody". Of course they tell somebody, then 
immediately tell that person "don't tell anybody", and the secret 
propapgates outward at the speed of voice relay, still carrying it's 
"privacy request" until the signal has degraded to the point where the 
always-useles privacy request fades away and is dropped from the 
message.

Consider instead the model of "Here's a coded secret, and a decoder 
ring". The receiver can pass the message on, but unless they take steps 
to also distribute the decoder ring, the information is not 
compromised. People being fundamentally lazy, they're less likely to 
make a copy of the decoder ring to send along too.

The PSTN to SIP gateway case may pass the confidential information on 
openly (since it's a trusting "closed" network, haha), but as soon as 
weg get to a potentially open network (i. e., IP) the information must 
be restricted to the privileged few who know the code. 

--
dean

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From: Matt Holdrege <[email-masked]>
Date: Fri, 25 Jan 2002 13:46:32 -0800

>transitive trust with my right brain so I'm likely to be suspicious of

Trust works in the PSTN today. Since we are talking about public 
telecommunications providers rather than enterprise or user trust, I don't 
see the problem.

>privacy, the SIP to PSTN gateway must honor it."

First of all, we aren't mandating procedures. We have no jurisdiction to do 
that. All I'm doing is describing possible procedures which may be mandated 
by governments. What we need to do is provide the protocol spec to 
accomplish what is needed.

That said, certainly the PSTN Gateway will likely have to deal with this. 
But additionally, a public SIP service provider *may* also have to support 
privacy restrictions. That means we have to forward the privacy indicator 
to the edge of the SIP service provider network.