Subject: RE: [Sipping] RE: Comments on draft-johnston-sipping-p2p-ipcom-01.txt

From: [email-masked]
Date: Tue, 5 Apr 2005 12:53:12 +0300

Hi,

Juha Heinänen wrote:
> 
> Paul Kyzivat writes:
> 
>  > Given common usage like this, perhaps there should be some 
>  > effort to formalize a convention that all URIs using the 
> "user@domain" 
>  > format should, if they exist, "belong" to the same owner 
> for each value 
>  > of "user@domain".
> 
> i support this idea, since i don't think that anyone likes 
> the idea that
> email identity is different from voice call identity.  this is big
> problem with many of the current voice services, such as skype.
> 

Yes, this would be a really good idea. At the moment this is generally true, but since it can't be relied upon, the common use of and interworking between various messaging technologies is really painful. sip: and mailto: are the most common examples, but there are other URIs (or wanna-be URIs) such as mmsto:, sms:, wv: and so on. 

In any case I've always found it quite problematic that most application layer identities are bound to a particular protocol or communication mechanism. tel: or E.164 with ENUM is nice in that sense that it gives some sort of uber-identifier that is not nailed to a particular protocol. 

I just wonder whether it is already too late to do something about this.

Markus

_______________________________________________
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: "Spencer Dawkins" <[email-masked]>
Date: Tue, 5 Apr 2005 07:06:38 -0500

So, does anyone on this list know of existing deployments with SIP 
URIs that don't/couldn't be tied to an e-mail address in the same 
domain?

> I just wonder whether it is already too late to do something about 

If it's not too late now, it probably will be soon - maybe we can do 
something quickly?

Spencer

---

From: Eunsoo Shim <[email-masked]>
Date: Tue, 05 Apr 2005 09:35:36 -0400

Well, some IP PBX systems use phone numbers in the URI like
[email-masked] which are different from and independent of their
email addresses. Isn't this an example?
Regards,

Eunsoo

Spencer Dawkins wrote:

> URIs that don't/couldn't be tied to an e-mail address in the same domain?
>

---

From: David R Oran <[email-masked]>
Date: Tue, 5 Apr 2005 10:49:07 -0400

> email addresses. Isn't this an example?
Only if they are not treated as aliases. I have a number of email 
aliases that all wind up at the same place:
[email-masked]
[email-masked]
[email-masked]

what I think people are saying is that the world is a much nicer place 
if
[email-masked]

were just another alias, and that it would work seamlessly for all of 
the following cases:

mailto:[email-masked]
sip:[email-masked]
mailto:[email-masked]
sip:[email-masked]

etc.

Dave.

>> If it's not too late now, it probably will be soon - maybe we can do
David R. Oran
Cisco Fellow
Cisco Systems
7 Ladyslipper Lane
Acton, MA 01720 USA
Tel: +1 978 264 2048
Email: [email-masked]

---

From: Eunsoo Shim <[email-masked]>
Date: Tue, 05 Apr 2005 12:17:26 -0400

Hi, David,

I am not opposing to the idea or wish but just providing an example in
which the idea may not work.

Another possible example may be a case when a phone is shared by
multiple people while they have all individual email addresses.

The PSTN model is that a number is assigned to a line or a terminal
while the email address is assigned to a person typically. A SIP URI can
be assigned to a person rather than a terminal but IP PBXs typically
replace the underlying technologies but not how the phones are used or
managed. Probably this brings the disparity.

Even if we cannot deduce the person's email address from the SIP URI
directly, still there is a way to find the email address as suggested by
Michael. So I guess the idea of using email as a way to leave a
voicemail is still valid assuming the person has a valid email address
and people like the way.

Regards,

Eunsoo

David R Oran wrote:

> what I think people are saying is that the world is a much nicer place if
> [email-masked]
>

---

From: "Stephen Sprunk" <[email-masked]>
Date: Tue, 5 Apr 2005 16:03:54 -0500

Thus spake "Eunsoo Shim" <[email-masked]>
> multiple people while they have all individual email addresses.

I would think the "correct" solution there is to have multiple SIP
identities ring on the same phone; if a user-specific one was used, it would
roll to the email for that user.

> The PSTN model is that a number is assigned to a line or a
> terminal while the email address is assigned to a person typically.
> A SIP URI can be assigned to a person rather than a terminal but
> IP PBXs typically replace the underlying technologies but not
> how the phones are used or managed. Probably this brings the
> disparity.

Unfortunately many of these systems don't even have a provision for
sip:user@domain URIs -- they work primarily or exclusively with
sip:number@server URIs.  However, such systems tend to have an optional
email field.  If filling this in correctly were required to receive
voicemail, people would do it.

> voicemail is still valid assuming the person has a valid email address

I don't think it's currently safe to assume someone's mailto URI is going to
have the same user/host parts as the SIP URI.  Would standardizing this
nudge implementors in the right direction or would it be tilting at
windmills?

S

Stephen Sprunk      "Those people who think they know everything
CCIE #3723         are a great annoyance to those of us who do."
K5SSS                                             --Isaac Asimov

---

From: Henning Schulzrinne <[email-masked]>
Date: Tue, 05 Apr 2005 20:04:45 -0400

> voicemail, people would do it.

At least the phones offered by a large network provider allow "real" 
URIs, albeit sufficiently painful in terms of user interface that I 
can't imagine anybody actually dialing them, but maybe people that send 
SMSs all day on a cell phone won't find the 12-digit entry method all 
that tedious.

> nudge implementors in the right direction or would it be tilting at

It seems a worthwhile operational recommendation. At the very least, you 
want to make sure that sip:[email-masked] -> mailto:[email-masked] 
doesn't actually deliver mail to [email-masked].

---

From: "Spencer Dawkins" <[email-masked]>
Date: Tue, 5 Apr 2005 22:43:24 -0500

> It seems a worthwhile operational recommendation. At the very least, 
> you want to make sure that sip:[email-masked] -> 
> mailto:[email-masked] doesn't actually deliver mail to 
> [email-masked].

This is the problem I'm thinking about.

Additional tightening might also be useful, but the first thing to 
tighten would be having e-mail go to someplace totally disjoint from 
the same user/host parts appearing in a SIP URI.

Spencer

---

From: "Stephen Sprunk" <[email-masked]>
Date: Tue, 5 Apr 2005 23:39:29 -0500

Thus spake "Henning Schulzrinne" <[email-masked]>
> > Unfortunately many of these systems don't even have a provision
> > for sip:user@domain URIs -- they work primarily or exclusively
> > with sip:number@server URIs.  However, such systems tend to
> > have an optional email field.  If filling this in correctly were
> > required to receive voicemail, people would do it.
>
> At least the phones offered by a large network provider allow
> "real" URIs, albeit sufficiently painful in terms of user interface
> that I can't imagine anybody actually dialing them, but maybe
> people that send SMSs all day on a cell phone won't find the
> 12-digit entry method all that tedious.

To paraphrase another contibutor here in a personal discussion, "Users don't
dial URIs any more than they dial phone numbers.  Everything is entered into
their directory (aka buddy list) and dialed by picking people out of a
menu."

If one accepts that worldview, and I agree that it's true in my age group
with cell phones, then the form of the URI is essentially irrelevant to the
user after first use.  It's convenient to have it predictable or easy to
enter, but not necessary.  Only its owner needs to memorize it.

OTOH, making sure that servers support non-numeric URIs transparently is
another matter.  Even the "large network provider" implementations I'm
dealing with won't route SIP calls outside their own network, nor do they
provide users with a URI that can receive outside calls.  They're just using
SIP as a replacement for ISDN (so far).

> > I don't think it's currently safe to assume someone's mailto URI
> > is going to have the same user/host parts as the SIP URI.
> > Would standardizing this nudge implementors in the right
> > direction or would it be tilting at windmills?
>
> It seems a worthwhile operational recommendation. At the very
> least, you want to make sure that sip:[email-masked] ->

It would be a good first step to prevent misrouting email; a bounce is
better than potentially sensitive information being forwarded to the wrong
person.  Creating disjoint user spaces or disjoint domains for SIP and SMTP
seems the "obvious" solution most admins will implement.

I think most sites are compliant with that already, though perhaps not in
the way we'd like.  i.e. all SIP URIs have a numeric user part (see above)
whereas all email usernames are non-numeric.

S

---

From: [email-masked]
Date: Wed, 6 Apr 2005 03:52:41 -0500

>most sites are compliant with that already, though perhaps not in

This completely ignores Presence and the capabilities derived from URLs. As
mentioned in this trail already, I don't want to remember several phone
numbers but only click on a name or icon.

Using phone numbers is not only broken, but also may bring all kind of
regulatory hassle that nobody needs to self inflict on their organization.

My two cents, Henry

-----Original Message-----
From: Stephen Sprunk [mailto:[email-masked]] 
Sent: Tuesday, April 05, 2005 11:39 PM
To: Henning Schulzrinne
Cc: [email-masked]; David R Oran
Subject: Re: [Sipping] RE: Comments on
draft-johnston-sipping-p2p-ipcom-01.txt

S

---

From: [email-masked]
Date: Wed, 6 Apr 2005 04:12:40 -0500

My two cents, Henry

-----Original Message-----
From: Stephen Sprunk [mailto:[email-masked]] 
Sent: Tuesday, April 05, 2005 11:39 PM
To: Henning Schulzrinne
Cc: [email-masked]; David R Oran
Subject: Re: [Sipping] RE: Comments on

S

---

From: Eunsoo Shim <[email-masked]>
Date: Wed, 06 Apr 2005 11:09:19 -0400

Stephen,

>roll to the email for that user.
Good idea. It will work.
It shows an example how phones (or phone numbers) should be managed a
little bit differently from PSTN to take advantage of full IP/SIP
capabilities.

>voicemail, people would do it.
Just out of curiosity, please let me ask you for pointers to example
systems requesting/providing an optional email field. So far, in my
limited exposure to (commercial) VoIP systems, I have not seen one of
such systems.
If many people are already associating SIP URIs to email addresses,
utilizing emails in association with SIP sounds more convincing.

Regards,

Eunsoo

---

From: Arjun Roychowdhury <[email-masked]>
Date: Wed, 6 Apr 2005 12:34:11 -0400

Eunsoo,
This actually may be a chicken-and-egg situation. Not many commercial
deployments derive email addresses from SIP ( I am aware of some
enterprise SIP systems that do, but very limited).

I think the point may be that once it is 'documented' by the IETF
(maybe in form of a BCP or informational draft ?) - it will make the
entire derivation process more structured and the vendors will be
comfortable with the mapping as something that goes beyond ad-hoc
interpretation.

regds
arjun

On Apr 6, 2005 11:09 AM, Eunsoo Shim <[email-masked]> wrote:
 
> Just out of curiosity, please let me ask you for pointers to example systems
> requesting/providing an optional email field. So far, in my limited exposure
> to (commercial) VoIP systems, I have not seen one of such systems.
> Sipping mailing list 
> https://www1.ietf.org/mailman/listinfo/sipping

-- 
Arjun Roychowdhury

---

From: Henning Schulzrinne <[email-masked]>
Date: Wed, 06 Apr 2005 13:05:06 -0400

I won't mention company names, but we (Dept. of Computer Science, CU) 
run a commercial system that relies on the identity of email and SIP 
user names, as it makes password notification much easier. Users can 
have any number of aliases, but their email address is always valid as a 
SIP URI if they have signed up. We already have enough "identity crises" 
without managing another namespace.

---

From: Eunsoo Shim <[email-masked]>
Date: Wed, 06 Apr 2005 13:46:07 -0400

Arjun,

What you said below sounds fine to me.

Some folks talked about maintaining the SIP URI as the email address
aliases.
The example system Henning described allows to use email addresses as
SIP URIs.

I think most phones will have only number pads for a while and thus most
people will still prefer to keep numeric phone numbers at least for the
timebeing. Of course, we prefer alphanumerics for our email addresses.
So in addition to one-way mapping/deduction from alphanumeric SIP URI to
the email address, maintaining name@domain and numbers(@domain) as
aliases for both of SIP URI and email address may pave the transition
path smoothly.

BTW, I heard there were WiFi phones with Skype Client. Does any one know
how they dial other Skype users' addresses with the phone?

Regards,

Eunsoo

---

From: Arjun Roychowdhury <[email-masked]>
Date: Wed, 6 Apr 2005 13:57:36 -0400

Ah well, the form factor debate :-)

In the overall scheme of things, I  believe as opposed to 'typing a
URI' vs 'dialing a number', dialing a number will continue to have
more support. Its just form factor convenience (the percentage of
people comfortable with graffiti sketching or miniscule qwerty keypads
is far less than those who find it easy to press a number keyboard
with just 10 digits 0-9).

However, I will admit that address book usage is becoming increasingly
common - and when you use that, the difference between URIs and
numbers diminishes to the user.

Those are my opinions on a wider scale of adoption. However, since
this thread is all about p2p-SIP, a network that does not exist, I am
willing to allow for some more lattitude (but just a little more, mind
you ;-)  that its conceivable that UAs for this new network are also
new and users in this segment may accept a new addressing
scheme/interface.

As regards to your Skype questions, the one's I read about were PDA
phones for a measly $800 or more. Again, Skype does allow you PSTN
numbers (or so I believe - I am not a subscriber) - so even
fat-fingered 10 digit dialing should work.

regds
arjun

On Apr 6, 2005 1:46 PM, Eunsoo Shim <[email-masked]> wrote:
> So in addition to one-way mapping/deduction from alphanumeric SIP URI to the
> email address, maintaining name@domain and numbers(@domain) as aliases for
> both of SIP URI and email address may pave the transition path smoothly. 
> 
> BTW, I heard there were WiFi phones with Skype Client. Does any one know how
> they dial other Skype users' addresses with the phone?
> 
> Regards,
> 
> Eunsoo
> 
> 
> 
This actually may be a chicken-and-egg situation. Not many
> commercial
deployments derive email addresses from SIP ( I am aware of
> some

I think the point
> may be that once it is 'documented' by the IETF
(maybe in form of a BCP or
> informational draft ?) - it will make the
entire derivation process more
> structured and the vendors will be
comfortable with the mapping as something
> that goes beyond ad-hoc
interpretation.

regds
arjun

On Apr 6, 2005 11:09
> AM, Eunsoo Shim <[email-masked]> wrote:

> systems
requesting/providing an optional email field. So far, in my limited
> exposure
to (commercial) VoIP systems, I have not seen one of such
> systems.
If many people are already associating SIP URIs to email
> addresses,
utilizing emails in association with SIP sounds more
> convincing.

Regards,

Eunsoo

Sipping
> mailing list
This list
> is for NEW development of the application of SIP
Use
> [email-masked] for questions on
current
> sip

 

-- 
Arjun Roychowdhury

---

From: Henning Schulzrinne <[email-masked]>
Date: Wed, 06 Apr 2005 14:01:38 -0400

Maybe you can start writing a draft describing the relationships of the 
various identifiers (tel, sip, email) and recommended practices. I'd be 
happy to contribute.

Basically, I think the rules are roughly:

- A SIP address MUST only have the same user and domain part of an email 
address for the same person or service, not some other individual or 
service.

- All SIP addresses SHOULD have a working email-equivalent, possibly 
restricted to non-telephone-URIs (i.e., those not starting with a digit).

- Some email addresses may not have SIP equivalents, e.g., because they 
don't support SIP services.

- Telephone numbers are mapped to SIP URIs without visual separators 
(hyphen, etc.), as partially described in the tel URI RFC and the SIP RFC.

Eunsoo Shim wrote:
> ------------------------------------------------------------------------
>

---

From: Eunsoo Shim <[email-masked]>
Date: Wed, 06 Apr 2005 14:30:27 -0400

>with just 10 digits 0-9).
I am with you about the above analysis.

>numbers diminishes to the user.
I also use the address book as much as I can when I use a cell phone.
But on the other hand I try to maintain my address book size not too
big, resulting in having to press numbers some times.
The address book will definitely reduce the burden of typing URIs on the
small key pad but will also have people less familiar to typing on the
key pad, making (maybe rare) occasions of typing URIs more painful. I am
sure it is not a problem at all to young people who can type 300
characters per minute on the cell phone.

>fat-fingered 10 digit dialing should work.
PDA phones...I see. Thanks. I was thinking of small cell phone type WiFi
phones.

Regards,

Eunsoo

---

From: Arjun Roychowdhury <[email-masked]>
Date: Wed, 6 Apr 2005 14:24:09 -0400

The document is a good idea. Would it be worth also addressing what
one needs to do when a GRUU is present as well in the failed
communication ?

regds
arjun

-- 
Arjun Roychowdhury

---

From: Jeremy George <[email-masked]>
Date: Wed, 6 Apr 2005 14:35:11 -0400 (EDT)

There is also an academic effort to make sip addresses the same as
campus standard email addresses.  www.internet2.edu/sip.edu

- Jeremy

On Wed, 6 Apr 2005, Henning Schulzrinne wrote:

> Date: Wed, 06 Apr 2005 13:05:06 -0400
> From: Henning Schulzrinne <[email-masked]>
> To: Eunsoo Shim <[email-masked]>
> Cc: David R Oran <[email-masked]>, [email-masked]
> Subject: Re: [Sipping] RE: Comments on draft-johnston-sipping-p2p-ipcom-01.txt
> 
> I won't mention company names, but we (Dept. of Computer Science, CU) run a 
> commercial system that relies on the identity of email and SIP user names, as 
> it makes password notification much easier. Users can have any number of 
> aliases, but their email address is always valid as a SIP URI if they have 
> signed up. We already have enough "identity crises" without managing another 
> namespace.
>
>> systems requesting/providing an optional email field. So far, in my limited 
>> exposure to (commercial) VoIP systems, I have not seen one of such systems.

---

From: "Stephen Sprunk" <[email-masked]>
Date: Wed, 6 Apr 2005 13:31:37 -0500

> Maybe you can start writing a draft describing the relationships
> of the various identifiers (tel, sip, email) and recommended
> practices. I'd be happy to contribute.
>
> - A SIP address MUST only have the same user and domain part
> of an email address for the same person or service, not some
> other individual or service.

I'd rearrange that to:

- A SIP address MUST NOT have the same user and domain parts as an email
address unless both refer to the same person or service.

> - All SIP addresses SHOULD have a working email-equivalent,
> possibly restricted to non-telephone-URIs (i.e., those not starting
> with a digit).

How about:

- The SIP address for a given person or service SHOULD have the same user
and domain parts as that person or service's email address.

> - Some email addresses may not have SIP equivalents, e.g.,
> because they don't support SIP services.
>
> - Telephone numbers are mapped to SIP URIs without visual
> separators (hyphen, etc.), as partially described in the tel URI
> RFC and the SIP RFC.

No problems with either of those.

S

---

From: "Stephen Sprunk" <[email-masked]>
Date: Wed, 6 Apr 2005 13:14:23 -0500

Thus spake Eunsoo Shim
> > Unfortunately many of these systems don't even have a
> > provision for sip:user@domain URIs -- they work primarily or
> > exclusively with sip:number@server URIs.  However, such
> > systems tend to have an optional email field.  If filling this in
> > correctly were required to receive voicemail, people would do it.
>
> Just out of curiosity, please let me ask you for pointers to
> example systems requesting/providing an optional email field.
> So far, in my limited exposure to (commercial) VoIP systems, I
> have not seen one of such systems.  If many people are already
> associating SIP URIs to email addresses, utilizing emails in
> association with SIP sounds more convincing.

I recall an optional "email" field when defining users in both Broadsoft and
Sylantro systems, though I don't have access to either at the moment to
verify if my memory is correct.  Perhaps someone working for either vendor
could confirm.

S

---

From: Eunsoo Shim <[email-masked]>
Date: Wed, 06 Apr 2005 15:05:08 -0400

Henning,

I'd be happy to do that. Your contributions will be greatly helpful and
appreciated.
You and other people already provided many good points in the list.

I have a quick question below.

> Maybe you can start writing a draft describing the relationships of
> the various identifiers (tel, sip, email) and recommended practices.
> I'd be happy to contribute.
>
> - A SIP address MUST only have the same user and domain part of an
> email address for the same person or service, not some other
> individual or service.
>
Do you mean equivalent email addresses within the same domain as the SIP
addresses?
Below are examples for clarification.

<SIP URI> ---- <equivalent email address>
[email-masked] ---- [email-masked] (OK)
[email-masked] ---- [email-masked] (OK)
[email-masked] ---- [email-masked] (OK)

In these three cases, the SIP URIs can be registered as aliases of the
equivalent email addresses easily.

[email-masked] ---- [email-masked] (OK ?)
[email-masked] ---- [email-masked] (OK ?)

The SIP URI and the email address have different domains in the last two
cases.
If myisp just provides VoIP but not the email service or Alice prefers
to use her job email address for all voice mails, the last two relations
should be allowed if a working email-equivalent is required for, let
say, the voice mail purpose.
What do you think?

> - Some email addresses may not have SIP equivalents, e.g., because
> they don't support SIP services.
>
Regards,

Eunsoo

---

From: Arjun Roychowdhury <[email-masked]>
Date: Wed, 6 Apr 2005 15:13:04 -0400

Instead of (or in addition to) all of this, why not just specify a
reccomendation that if a SIP call fails to  connect you to a user,
then in the 3xx or 4xx response, there is a well defined mechanism
that allows you to specify a contact email address which the sender
then can use if needed ? The advantage then is that domain similarity
requirements and such go away, and I can still use my compuserv email,
which may well be  [email-masked] for my SIP id, which is
a refined [email-masked]

This will also avoid mail bounces to a great degree for systems that
do not support such a direct translation.

regds
arjun

-- 
Arjun Roychowdhury

---

From: Henning Schulzrinne <[email-masked]>
Date: Wed, 06 Apr 2005 15:14:17 -0400

> Do you mean equivalent email addresses within the same domain as the SIP

Yes; it would be nice to be able to take a valid sip:user@domain and
construct mailto:user@domain, which may well be an alias for
mailto:realuser@domain, just like many domains have multiple email
addresses for the same user (e.g., john.doe@, jdoe@, john_doe@, doe@).

> equivalent email addresses easily.

The mapping is up to the SMTP server and not visible externally, so I
don't think we have to be too concerned about the details.

> [email-masked] ---- [email-masked] (OK ?)

It doesn't matter if the SMTP server does a redirect or forwarding to
some other address.

---

From: Henning Schulzrinne <[email-masked]>
Date: Wed, 06 Apr 2005 15:21:45 -0400

Not sure why a GRUU matters here. Failed communication is only one 
reason for this equivalence - usage of certificates (that often rely on 
mail reachability) and similar proof-of-control applications all benefit 
from this.

Also, this should presumably extend not just to sip: and mailto:, but 
also pres: and im:. One can discuss whether the AAA ID (NAID?) is also 
related.

I vaguely recall that one of the items that caused concern in this 
discussion at some earlier version of this discussion is that the syntax 
of these address format, in particular the user part, differ subtly. In 
other words, I believe that all 'modern' (2821/2822) email identifiers 
are valid SIP user names, but I'm not positive whether the converse is 
true. As a random example,

[email-masked]

is probably a legal user name (equivalent to 'John Doe'), but use in 
2821/2822 is less clear.

---

From: Arjun Roychowdhury <[email-masked]>
Date: Wed, 6 Apr 2005 16:21:41 -0400

Henning,
Here was the thought:

the GRUesome Uri could be provided by a callee to the caller during a
normal dialong exchange. Lets say that sip:[email-masked] received a
GRUU from sip:[email-masked] and that happens to be
sip:hha9s8d=[email-masked].

Now if bob tried to and failed to address alice due to some reason
(assuming he got a 4xx back), then if bob were to followup with an
email, the URI of the request was the GRUU - will likely will make no
sense to send an email to. Instead, maybe then bob should try the To
header ? (which again has assertion of identity to think about)

regds
arjun

-- 
Arjun Roychowdhury

---

From: Eunsoo Shim <[email-masked]>
Date: Wed, 06 Apr 2005 17:05:21 -0400

With a SIP proxy serving the target UA, certainly the response message
can be used to deliver the email address as you said below.
My guess is that the recommendations to associate SIP URI, email
addresses, and telephone numbers for the same person (owner) may make
many things simpler.
But back to the initial motivation of this discussion, the starting
point was how to leave a voicemail in P2P SIP where no one will send any
response message when the target UA is simply offline.

Regards,

Eunsoo

---

From: Arjun Roychowdhury <[email-masked]>
Date: Wed, 6 Apr 2005 17:07:12 -0400

Eunsoo, we really should be breaking this problem set into two discrete areas:

a) What it takes to leave a voicemail in a P2P system

b) What it takes to map SIP addresses to non SIP addresses

The motivation of b) is not _only_ a) and therefore, b), which I
assume is the draft you will be writing, should discuss it from a
general mechanism, which therefore, should include 1) guessing the URI
on conventions specified 2) Being told what the alternate URIs are if
the called UA is available to tell you the same [and if so, its much
safer than guessing]

regds
arjun

On Apr 6, 2005 5:05 PM, Eunsoo Shim <[email-masked]> wrote:
> With a SIP proxy serving the target UA, certainly the response message can
> be used to deliver the email address as you said below.
> My guess is that the recommendations to associate SIP URI, email addresses,
> and telephone numbers for the same person (owner) may make many things
> simpler.
> But back to the initial motivation of this discussion, the starting point
> was how to leave a voicemail in P2P SIP where no one will send any response
> message when the target UA is simply offline.
> 
> Regards,
> 
> Eunsoo
> 
> 
then in
> the 3xx or 4xx response, there is a well defined mechanism
that allows you
> to specify a contact email address which the sender
then can use if needed ?
> The advantage then is that domain similarity
requirements and such go away,
> and I can still use my compuserv email,
which may well be
> [email-masked] for my SIP id, which is
a refined
> [email-masked]

This will also avoid mail bounces to a great
> degree for systems that
do not support such a direct
> translation.

regds
arjun

On Apr 6, 2005 3:05 PM, Eunsoo Shim
> <[email-masked]> wrote:
 
> Henning,

I'd be happy to do that. Your contributions will be greatly
> helpful and
appreciated.
You and other people already provided many good
> points in the list.

> Maybe you can start writing a draft describing the relationships of
the

- A SIP
> address MUST only have the same user and domain part of an
email address for
> the same person or service, not some other
individual or service.

- All SIP
> addresses SHOULD have a working email-equivalent, possibly
restricted to
> non-telephone-URIs (i.e., those not starting with a digit).

addresses?

<SIP URI> ----
> <equivalent email address>
[email-masked] ---- [email-masked]
> (OK)
[email-masked] ----
> [email-masked] (OK)

In these three cases, the SIP URIs can be registered
> as aliases of the

[email-masked] ----
> [email-masked] (OK ?)
[email-masked] ---- [email-masked] (OK
> ?)

The SIP URI and the email address have different domains in the last
> two
cases.
If myisp just provides VoIP but not the email service or Alice
> prefers
to use her job email address for all voice mails, the last two
> relations
should be allowed if a working email-equivalent is required for,
> let

> - Some email addresses may not have SIP equivalents, e.g., because
they
> don't support SIP services.

- Telephone numbers are mapped to SIP URIs
> without visual separators
(hyphen, etc.), as partially described in the tel
> URI RFC and the SIP
RFC.

Eunsoo

 

-- 
Arjun Roychowdhury

---

From: Eunsoo Shim <[email-masked]>
Date: Fri, 08 Apr 2005 12:11:19 -0400

Hi, Arjun,

I agree with you about the separation and, as you said, the address
mapping will be the focus for my writing.
Regards,

Eunsoo

Arjun Roychowdhury wrote:

>>various identifiers (tel, sip, email) and recommended practices.
>>    
>>
>I'd be
>  
>
>>happy to contribute.
>>    
>>
>