Subject: RE: [Sip] draft-ietf-sip-asserted-identity-01

From: "Peterson, Jon" <[email-masked]>
Date: Fri, 14 Jun 2002 12:31:30 -0500

Good morning all,

The proposition that Juha put forward to which I responded in my last mail -
that a service provider will bill me at a lesser rate if I select a
favorable area code in my calling party number - is absurd: the service
provider knows who you are, knows the area codes you can claim in your
calling party number, and it seems unlikely that they are granting this
flexibility so that you can elect to pay them less money.

The milder proposition that Juha subsequently put forward - that a user will
select between multiple identities for some unspecified reason, maybe
something like charge number (see below) - is essentially what 3GPP is
doing, as Keith and others have pointed out. 

I hope that all these people eagerly leaping to Juha's defense intend to
champion the former proposition, the one that was actually attacked, not the
latter proposition.

If you argue from absurdities, I think you should expect that people on this
mailing list with either ignore you or tell you to stop. I don't think it
really matters what you are arguing for. I'm not trying to shut down
rational discussion about this matter - but I also think we shouldn't waste
our time when discussion is clearly in the twilight zone.

Also, I'd ask people to remember that Juha put forward these examples in
order to argue (as I understand it) for one point: that we need a baseline
SIP identity mechanism distinct from any currently available way of
expressing identity, and that therefore P-Preferred-Identity should not be a
P- header.

So let's examine Juha's best proposition to date - the 'charge number'
example - in the light of this desired conclusion. We all no doubt agree
that you should be able to specify an identity in SIP signaling that
indicates the party responsible (in a legal and financial sense) for the
call. I think that the authenticated identity, the one that you can
cryptographically prove, probably should be the identity to which a call
will be billed - you would want a SIP baseline mechanism for ascertaining
the responsible party to have cryptographic properties, anyway, so that it
can't be trivially spoofed. There is no obvious reason why a charge number
should be distinct from the identity I provide when I authenticate - again,
you can have multiple charge numbers to choose from, and use the same shared
secret for each one of them if you'd like. I would say this though - if I
were designing a way in which users could express a 'work' and 'home' charge
number, I think it would be desirable to have different credentials for
personal identities than for corporate charge numbers. In many architectures
and under many policies, companies probably wouldn't like people to be able
to charge calls to them on the strength of their personal credentials (which
might use weak password schemes, etc).

I see this example as further validating the use of SIP authentication is
the baseline spec to express this form of identity, not as an argument for
the standardization of some other way of expressing identity in baseline SIP
(which is of course what this whole argument is about). While we all agree
that it would be nice to have a charge-number, it isn't at all clear that we
need to add new headers to baseline SIP in order to get one.

Jon Peterson
NeuStar, Inc.

> -----Original Message-----
> From: [email-masked] [mailto:[email-masked]]
> Sent: Friday, June 14, 2002 7:58 AM
> To: Peterson, Jon
> Cc: [email-masked]'; [email-masked]
> Subject: RE: [Sip] draft-ietf-sip-asserted-identity-01
> 
> 
> 
> 
> 
> 
> >So, you're honestly trying to tell me that users will save on
long-distance
> >charges depending on how they hint at their calling party number? Do you
> >actually work for a telephone company?
> 
> Personal and work accounts perhaps. The caller may not be the one paying
> for the call. He may be working for others who have negotiated their own
> arrangements.
> 
> 
> 

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---

From: [email-masked]
Date: Mon, 17 Jun 2002 22:30:24 +0300

> flexibility so that you can elect to pay them less money.

in many cases the party that provides the sip proxy that authenticates
the user and lets the user to selects its sip identity has nothing to
the with the party that provides the pstn service.  the pstn service
provider simply charges based on called and calling party numbers and
doesn't know anything about the sip user and certainly doesn't do any
favors for him/her.

-- juha