Subject: RE: [Sipping] Identity relationships

From: "Francois Audet" <[email-masked]>
Date: Mon, 11 Jul 2005 20:39:12 -0500

Hi Henning, Eunsoo

Some minor comments on section 3.7:

- Your example of the SIP URI is missing the domain name.

- I believe that when mapping a tel URI into a SIP URI, one MUST
(instead of SHOULD)
  add the user=phone parameter. 

- You state "mapped without the visual separators". While I think this
WOULD have
  been a good idea to avoid having to parse the username and just do a
  basic string comparison, this is not what 19.1.6/RFC 3261 says,
unfortunately. In
  fact, all the examples use the visual separators. Therefore, your
section should
  include some discussion about visual separators, because it is an
issue.
  Specifically, it needs to say that when username is a phone number,
the visual
  separators need to be ignored. Maybe some "equivalency" examples with
or without
  the separators would be useful. I will note that this is one more
reason why the
  user=phone parameter should be a MUST for a tel URI-derived SIP
address, otherwise
  you have no way for sure to know if the visual separators can be
ignored or not.

> -----Original Message-----
> From: [email-masked] 
> [mailto:[email-masked]] On Behalf Of Henning Schulzrinne
> Sent: Monday, July 11, 2005 16:49
> To: SIPPING LIST
> Subject: [Sipping] Identity relationships
> 
> 
> An initial exploration into user-interface issues related to 
> identifiers 
> is written up in
> 
> http://www.ietf.org/internet-drafts/draft-schulzrinne-sipping-
id-relationships-00.txt

This is more operational than protocol-defining, primarily to minimize 
user confusion, as users don't think in protocols (or shouldn't have 
to). There are other related issues, such as certificates, that we have 
not yet explored.

Henning

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_______________________________________________
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: Arjun Roychowdhury <[email-masked]>
Date: Tue, 12 Jul 2005 10:30:41 -0400

Some initial comments:

Section 3:
- In recc. practices, why are only sip: and mailto: addresses mentioned ?
Should there not be examples of "im:" {aim,yahoo,xmpp,etc) as well ?

- Why is it that each requirement specifies a MUST NOT as well as a MUST ?
For example, instead of saying "[email-masked] MUST NOT be used for both sip
and email unless they refer to the same person. Therfore, [email-masked] MUST
be used for both sip and email only if its for the sme person" why not
just use the MUST part ?

3.3  - I don't understand the point of this. Since its not possible to
guess the email-equv of a SIP address (if it exists), why is there a
need to say a SIP address should have a corr. email address ? For
example, I may be [email-masked] and my email, from another
provider may be [email-masked] Since there is no name relation
here, not sure what we acheive by stating this.

3.7 - since its a telephone number description, does it make sense to
move it just after 3.4, since it deals with phone nos (even if its not
specifically a tel)

---

From: Henning Schulzrinne <[email-masked]>
Date: Tue, 12 Jul 2005 14:59:41 -0400

Thanks for your comments. Some remarks inline below.

> Should there not be examples of "im:" {aim,yahoo,xmpp,etc) as well ?

The problem is that we don't have official non-SIP/XMPP URI schemes. I 
don't see how im: is useful without some kind of ENUM-like mapping 
mechanism. If I see im:[email-masked] on a webpage, what should I do 
with that, given that I have no clue which IM protocol Alice might support?

XMPP should be mentioned consistently throughout.

> be used for both sip and email only if its for the sme person" why not

This was just for emphasis, but this can probably be simplified by 
removing the double negative (first sentence).

> here, not sure what we acheive by stating this.

This is probably one of the areas that requires the most discussion. The 
general motivation is that users shouldn't (and don't) think of URIs, 
they should (and do) think of identifiers. Thus, longer term, if I 
happen to know your email identifier, it would help communication if I 
could also try this for SIP and get something useful, if only a redirect.

This does not preclude that you have several different addresses and 
that you might prefer [email-masked] for email and [email-masked] 
for Skype/IM/presence.

One could also argue that provider-based identifiers are a short-term 
crutch. Why should my externally visible identity depend on who happens 
to receive my SMTP or SIP requests? Most people would object if you had 
to dial somebody as "Verizon 12345" (at least without being paid by 
Verizon for doing the advertising for them). Almost all web hosting 
providers offer email redirection; it would be nice if they also offered 
SIP and XMPP redirection.

> move it just after 3.4, since it deals with phone nos (even if its not

Probably.

---

From: Eunsoo Shim <[email-masked]>
Date: Tue, 12 Jul 2005 15:38:51 -0400

I also appreciate Arjun's comments.
My angle of view on rule 3.3 is described after your comments in the below.

> This is probably one of the areas that requires the most discussion. 
> The general motivation is that users shouldn't (and don't) think of 
> URIs, they should (and do) think of identifiers. Thus, longer term, if 
> I happen to know your email identifier, it would help communication if 
> I could also try this for SIP and get something useful, if only a 
> redirect.
>
> that you might prefer [email-masked] for email and 
> [email-masked] for Skype/IM/presence.
>
> crutch. Why should my externally visible identity depend on who 
> happens to receive my SMTP or SIP requests? Most people would object 
> if you had to dial somebody as "Verizon 12345" (at least without being 
> paid by Verizon for doing the advertising for them). Almost all web 
> hosting providers offer email redirection; it would be nice if they 
> also offered SIP and XMPP redirection.
>
>
You must remember that the discussion of identifier mapping started from 
the idea of leaving voicemail by email in P2P IP telephony systems back 
in April. For the application, an email address of the voicemail 
recipient can be used even if the email address has different user and 
domain parts. This kind of application was what motivated this 
recommendation in my mind.

As discussed in the mailing list at that time, there could be various 
ways (like ENUM or explicit indications in the SIP messages) to enable 
the sender to get to know the email address associated with a particular 
SIP address but guessing would not work. Such specific mechanisms for 
this are not in scope of this draft. I notice now that this 
recommendation is a little bit different from other recommendations in 
the sense that it requires (a) mechanism(s) for mapping to be useful.

Regards,

Eunsoo