[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Enum] Re: [Geopriv] Re: [Simple] tel URIs in common policy

inline.

Stastny Richard wrote:


All of this discussion is making it clear that there is a MUCH bigger
mess here that needs attention, around phone number usage,
interpretation and equivalence across tel and SIP URI. This is a common
source of interop problems in the wild and it makes sense to address it.



I fully agree. At voipeer the question is raised what format to use
if E.164 or phone numbers in general are to be transmitted between peers.
also in the to: field

I see this probably as having little to do with peering. Its a problem in general for SIP, and confusion on the interpretation exists between clients and there proxies, proxies and proxies, and so on.



However, the problem at hand is to complete the common policy document,
and it seems to me a mistake to hold up common policy until that mess is
sorted out. Furthermore, I would argue that the common policy spec is
not the place where that mess should be sorted out.



Could this be done in voipeer ? Or at least partially
The problem is that only a special aspect of the semantic
of the usage of these URIs is under discussion;
namely the usage for signalling

Per above, I think that is a mistake. Sorting out the differences between tel URI, SIP uri with and without user=phone, and so on, are general sip problems.

Stepping back for a sec, I think there are real differences between the
tel URI and the sip version. The way to think about it is that the tel
URI is a NAME, and you need to think of it as if it were a URN. A SIP
URI is an address. Procedures like enum allow the resolution of a name
to an address.


Hmm. We should not go down this path ;-? This is not so simple: This is also a terminology problem between differnent standard bodies

A phone number could also be a name and  an address, In ITU and
ETSI terms a sip AoR or email address is also a name. Only an IP-address
is an address.

There are addresses at all layers in the stack. We have IP addresses, but also MAC addresses. You translate from one to the other. Something is an address when it identifies an object by its location. In that sense, the SIP URI is fundamentally an address, in that the presence of the domain part indicates that we are identifying something by its location.


Also with SIP URIs you may have:

A. A SIP AoR, which is a name
B. A SIP Contact Address, which is either a name or an (IP) address
C: A SIP URI with parm user=phone, which is a phone number (a name?)
D. A GRUU, which is ?

Actually based on the definitions above, all are addresses, even an AoR. After all, the A in AoR stands for "address".



As such, it really makes no sense to compare a name and an address. Just
because I work at 600 Lanidex Plaza in Parsippany, does that make
"Jonathan Rosenberg" (a name) equivalent to "600 Lanidex Plaza,
Parsippany, NJ 07054"? Definitely not. So, I would argue that the tel
URI and SIP URL are NEVER equivalent; you need to convert the name to an
address for comparison.



I cannot fully follow this argument:

Lets try it in another way. There is other usages for URIs

A. You put it on a webpage to be clicked on:
In this case you would either use a plain tel URI to indicate a phone number
or a sip URI in the format sip:userID at foo.bar to indicate rachability via sip
In the first case the client linked to the tel URI may even chose to use a dialler
in the second case it wold indicate to use a sip-client. If you use
sip:+1-232-555-1234 at foo.com;user=phone , this would indicate also to use
the sip client?

The usage of a URI for different applications is quite separate from whehter a URI represents a name or an address, and separate still from equality rules for these things.

My point is that I think it makes sense to consider the tel URI a URN, and that it is merely an accident of history that it wasn't a URN more properly. Now, as you and I both know phone numbers in the PSTN are abused to represent lots of things, but there is no reason to carry forward this confusion into voip. This is why I am proposing that when a phone number is in a tel URI, it represents a name. We don't know where it is on the network (indeed even if its on an IP network). To know that, we translate to an address. That address is a SIP URI. That SIP URI can contain a phone number, i.e. sip:+19739525000 at provider.net;user=phone, however in this format the phone number has been resolved to an address. The act of porting a number is a change in the translation of the phone number as a name (the tel URI) to the phone number as an address (the SIP URI).




B: in ENUM. (now we are finallyat the point ;-)
If one queries ENUM for the phone number +1-232-555-1234
it would be completely useless to get back the same number in tel:+1-232-555-1234

Agree. My point is exactly this; had tel URI been a URN proper, than enum would exactly be the resolution service for resolving that URN scheme to a SIP URI.


we need here sip:+1-232-555-1234 at foo.com;user=phone with
the same number to indicate the foo.com domain of the carrier
This is basically the essential information


Right, and this is an address.


Givne this, the meaning of sip:<phone-number>@domain;user=phone means
that the domain is asserting ownership of the identity in the user part,
in this case a global phone number. As such, its appropriate to use this
form only when it is authoritatively known that the domain in question
"owns" that phone number.



This is a very interesting aspect, leading to the CLI and CLIR problem
not yet discussed fully in voipeer.


I don't follow what you are talking about here.


The CLI problem is IMHO definitely in scope of voipeer. CLI is required
for call-back (especially if gatewaying to the PSTN), for MCI to emergency services
and also requires CLIR support for anonymous calls.

We have numerous specs covering conveyance and assertion of identities. See in particular draft-rosenberg-sip-identity-privacy which talks about how to properly support anonymous calling with draft-ietf-sip-identity.

-Jonathan R.

--
Jonathan D. Rosenberg, Ph.D.                   600 Lanidex Plaza
Director, Service Provider VoIP Architecture   Parsippany, NJ 07054-2711
Cisco Systems
jdrosen at cisco.com                              FAX:   (973) 952-5050
http://www.jdrosen.net                         PHONE: (973) 952-5000
http://www.cisco.com

_______________________________________________
enum mailing list
enum at ietf.org
https://www1.ietf.org/mailman/listinfo/enum