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

From: "Chiou, Mark" <[email-masked]>
Date: Thu, 24 Jan 2002 14:15:05 -0600

Hi All,

For Address presentation information, can we use the DISPLAY-name field
in the name-addr header to store calling name and number? 
	For example, 
		From : Anonymity, 1234567<sip:@bell.com>;tag=3pcc  
			--- to indicate restriction on calling number
Then SIP-to-ISUP gateway can build "Address presentation information"
from extracting calling number from From's DISPLAY name field if the
number is missing from userinfo and set the Address presentation to
restricted.

My 2 cents thought,

Mark Chiou

-----Original Message-----
From: Flemming Andreasen [mailto:[email-masked]]
Sent: Thursday, January 24, 2002 12:54 PM
To: Christian Huitema
Cc: Juha Heinanen; Dean Willis; [email-masked]; [email-masked]
Subject: [Sip] Re: [Sipping] calling number blocking at sip/isup gateway

Christian Huitema wrote:

> > ok, i tried again and still can't figure out how my proxy can tell
to
> a
> > trusted sip/isup gw that the calling user doesn't want his/her phone
> > number to be shown to the called pstn user.  i would like to be able
> to
> > do something simple in the proxy, like adding a header
> >
> > Anonymity: from
> >
> > to the invite, but that kind of thing is not available.  my
suggestion
> > is that the authors of the privacy i-d and the sip-isup i-d figure
it
> > out how to map isup Calling party indicator "Address presentation
> > restricted" to/from sip.  before that is done, i would not vote
going
> > forward with either i-d.
>
> There is an obvious tension between four issues:
>
> - The fact that when an UA is under the user's control, the content of
> the header fields can be set to arbitrary values, and that any header
> field can be expected to be read by the final user;
> - The legal requirement in many countries for "traceability", i.e. the
> possibility for law enforcement to find the source of any phone call;
> - The desire in many cases to place anonymous calls, i.e. without
> disclosing the identity and/or the location of the caller (Think
> "whistle blower");
> - The desire in even more cases to block anonymous calls (Think spam).
>
> The mix of the four makes for an unsavory soup. In the privacy draft,
> the law enforcement requirement can only be met by letting a proxy
> insert a "Remote-Party-ID" header; but the moment you do that, you
> enable every party down the chain to see and display that header. To
> prevent abuse, the draft creates a "RPID-Privacy" header that the
caller
> should set to the appropriate value if it does not want the
information
> casually displayed.
>
> Frankly, I am amazed by the naivety of the proposal. To make this
work,
> you then need a "chain of trust" between all the proxies;

Not all the proxies - only the proxies within your trust boundary. As a
special case of this, a proxy may not trust any other proxies and hence
always encrypt the Remote-Party-Id with privacy indication before
forwarding
the message.

> yet, we have
> no mechanism to determine this level of trust. We also need to assume
> that the information will not be displayed by the called UA regardless
> of the value in the privacy field,

No. There is an explicit distinction between forwarding messages to
trusted
and non-trusted entities. Whenever you forward a message to an untrusted
entity, and privacy has been requested, you will encrypt the
Remote-Party-ID
information. It's never passed in clear to an untrusted entity.

> which goes contrary to what we see
> with e-mail, and also goes contrary to the obvious desire to fight
spam.
>
> Frankly, I don't find this privacy draft useful or adequate. It
attempts
> to comply with telephony-era regulations that have basically no
meaning
> in the Internet. In fact, we could probably meet these regulations by
> having a much simpler solution that directly target ISUP
compatibility:
> a calling telephone number header, with a privacy tag, that gateways
to
> the telephone network could directly translate.
>

This doesn't change any of the fundamental problems and solutions in the
draft. All you are saying, is that the only identity information that
can be
provided and protected are telephone-numbers. The more general SIP-URLs
will
not have this ability and hence cannot be used if we wanted to provide a
similar service. I don't think that's very compelling.

-- Flemming

PS: This discussion should probably be moved to the SIP list.

>
> -- Christian Huitema
>
> _______________________________________________
> Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
> 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

--
Flemming Andreasen
Cisco Systems

_______________________________________________
Sip mailing list  https://www1.ietf.org/mailman/listinfo/sip
This list is for NEW development of the core SIP Protocol
Use [email-masked] for questions on current sip
Use [email-masked] for new developments on the application of sip

_______________________________________________
Sipping mailing list  https://www1.ietf.org/mailman/listinfo/sipping
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

---

From: Juha Heinanen <[email-masked]>
Date: Thu, 24 Jan 2002 22:40:58 +0200

> number is missing from userinfo and set the Address presentation to

if this is how people want to do it, then it should be clearly
documented in the sip-isup i-d.

-- juha