Subject: Re: Summary of RE: [Sip] Comment, SIP Privacy draft

From: [email-masked]
Date: Fri, 12 Apr 2002 14:26:57 EDT

In a message dated 4/12/02 11:53:16 AM Eastern Daylight Time, 
[email-masked] writes:

> The point I'm trying to make is that To and From are USER supplied 
> information. The Service Provider doesn't insert them, inspect them, or 
> have any responsibility for them. Insisting that the service provider 
> change them is just like insisting that the service provider change any 
> other user-supplied information, such as the words I'm typing now. Anything 
> I put in my To or from field is deliberately and explicitly intended to be 
> delivered to the terminating side of the dialog, and if as a service 
> provider you FAIL to do that, then you have DAMAGED my data, and my lawyers 
> will be in touch!
>  
> The calling-party-identity presentation infromation (CLIP or RPID) is NOT 
> inserted by the user. It is inserted by the network, WITHOUT THE CONSENT of 
> the user. As such, the operator is responsible for the protection of that 
> information in a manner consistent with regulation and the expressed wishes 
> of the user.
>  
> The calling-line-identity-restriction information (CLIR or Privacy) is a 
> means by which the user expresses wishes with respect to the handling of 
> NETWORK provided information.
> 

In a message dated 4/12/02 11:33:03 AM Eastern Daylight Time, 
[email-masked] writes:

> The problem with this line of thinking is that in the PSTN, identity is 
> always asserted by
> the network, and never by the UA.  In SIP, presently, identity is always 
> asserted by
> the UA and never the network.  Privacy when you have network asserted 
> identity
> means something different than when you have user asserted identity.
> 

There seems to be some confusion about the current "PSTN" situation. True, in 
the POTS PSTN (analog lines) the user doesn't actually include their identity 
in the signaling to the network. But, since the identity is directly 
associated with the physical phone line, it's the same thing. The telephone 
company simply converts its knowledge of the identity of the wire into a 
telephone number and goes from there.

In ISDN, on the other hand, the user can include their identity (phone 
number) in the signaling, since each physical interface and each device can 
support multiple telephone numbers. The number is put in the Calling Party 
Number field. The network may screen this number to make sure it is a valid 
number for that interface. Depending on the result of the screening, the 
network may include multiple numbers in the call set up, for example, an 
unverified user provided number and the network provided valid number.

The user may specify by per-call signaling or by a permanent subscription 
option whether or not they want the network to apply the restriction 
("privacy") feature to this identity (whether the identity came from the user 
or was added by the network or both doesn't matter). There is no attempt to 
also apply "privacy" if the user chooses to put some other identifying 
information in the User-to-user field.

We have to decide whether the From/To fields are like the Calling Party 
Number field in ISDN (meant for user-network signaling and left to the 
network to change if required by the service) or are they like the 
User-to-user field in ISDN (never touched by the network). I've heard both 
sides of the argument being made, so there is apparently not a consistent 
view on how basic SIP works.

It seems that the added RPID field is similar to the network added (verified) 
number in ISDN.

Mike

---

From: "Dean Willis" <[email-masked]>
Date: Fri, 12 Apr 2002 14:37:40 -0500

Mike wrote:
---------------------- 
There seems to be some confusion about the current "PSTN" situation.
True, in the POTS PSTN (analog lines) the user doesn't actually include
their identity in the signaling to the network. But, since the identity
is directly associated with the physical phone line, it's the same
thing. The telephone company simply converts its knowledge of the
identity of the wire into a telephone number and goes from there. 

In ISDN, on the other hand, the user can include their identity (phone
number) in the signaling, since each physical interface and each device
can support multiple telephone numbers. The number is put in the Calling
Party Number field. The network may screen this number to make sure it
is a valid number for that interface. Depending on the result of the
screening, the network may include multiple numbers in the call set up,
for example, an unverified user provided number and the network provided
valid number. 

The user may specify by per-call signaling or by a permanent
subscription option whether or not they want the network to apply the
restriction ("privacy") feature to this identity (whether the identity
came from the user or was added by the network or both doesn't matter).
There is no attempt to also apply "privacy" if the user chooses to put
some other identifying information in the User-to-user field. 

We have to decide whether the From/To fields are like the Calling Party
Number field in ISDN (meant for user-network signaling and left to the
network to change if required by the service) or are they like the
User-to-user field in ISDN (never touched by the network). I've heard
both sides of the argument being made, so there is apparently not a
consistent view on how basic SIP works. 

It seems that the added RPID field is similar to the network added
(verified) number in ISDN. 
------------------------ 

Excellent summary, Mike. That's exactly what I'm saying.

In short:

To:/From: are equivalent to ISDN user-to-user data, as is most of
current SIP.

RPID: is analogous to CPN, and its "Screened" parameter analogous to
what happens in ISDN today.

Privacy: is analogous to the calling line identification restriction
flag.
 
I think an understanding of this relationship should clear up 99% of the
debate over the "privacy" draft, which is really much more of a SIP-T
"telephony interworking" document than it is a general privacy document.

--
dean

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