Subject: [SIP] Redirect server returning new From header

From: Christer Holmberg <[email-masked]>
Date: Tue, 24 Oct 2000 11:05:36 +0300

Another proposal on the issue, with another use of the "Also-From"
header.

Currently, a redirect server add a new Request-URI (in the 3xx response
Contact header) to the UAC. An idea would be that it could also return a
new From header, for example with a telephone number. In this case, the
UAC, and intermediate proxies, would not need to insert any extra
headers or URI parameters in the request. This would be a new, optional,
feature in a redirect server.

Comments?

Christer Holmberg
Ericsson Finland

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From: Anders Kristensen <[email-masked]>
Date: Tue, 24 Oct 2000 11:14:21 +0200

> feature in a redirect server.

A registrar is free to return SIP, tel:, mailto:, http: and any other
kind of URLs in Contacts. Whatever it is you think you need the extra
From for I think you'll find you can use Contact for.

Anders

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From: Christer Holmberg <[email-masked]>
Date: Tue, 24 Oct 2000 12:38:31 +0300

Hi,

>Do you actually mean the From: or do you mean the To:?

From.

>It seems a bit odd for a redirect server to tell the UAC what
>From: to use. Perhaps you could give an example of its usage.

Well, this is - once again - related to the PSTN/SIP GW issue, if the GW
needs a telephone number for some kind of A number analysis. When I make
a phone call from my SIP phone I may not know that the call may end up
on the PSTN side, so I can for example put my email address in the From
header. However, since the network architecture includes a GW to the
PSTN network, somewhere there could be a server which is able to do the
mapping between the email address user part and a telephone number user
part (if SIP URL is used).

Regards,

Christer Holmberg
Ericsson Finland

> 
> Regards,
> Sean
> 
> --
> Sean Olson <[email-masked]>
> 
> Christer Holmberg wrote:
>

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From: Christer Holmberg <[email-masked]>
Date: Tue, 24 Oct 2000 14:01:51 +0300

Hi,

>From for I think you'll find you can use Contact for.

I know, but the idea was to give the possibility not only to return a
new RequestURI - whatever format - in the Conact header, but also to
give a new From header, if for example the Redirect server knows that
the request will reach a PSTN/IP GW, and the current From header can for
example not be used for A number analysis.

I want to point out that this case is not about solving a bug in the
protocol itself, it has to do only with the interworking architecture
with PSTN.

Regards,

Christer Holmberg
Ericsson Finland

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From: "Hisham Khartabil" <[email-masked]>
Date: Tue, 24 Oct 2000 14:29:06 +0300

Hi,

I see what you are trying to achieve here, but my concern is with the
redirection rules.  When a UA gets a 3xx response, it issues a new request.
MUST that new request belong to the same call leg as the original request?
ie: same To: From: Call-id, but higher Cseq.  If so, your proposal breaks
that rule.

Regards,
Hisham

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On
Behalf Of Christer Holmberg
Sent: 24. lokakuuta 2000 14:02
To: [email-masked]
Cc: Anders Kristensen
Subject: Re: [SIP] Redirect server returning new From header

Hi,

Regards,

Christer Holmberg
Ericsson Finland

---

From: Christer Holmberg <[email-masked]>
Date: Tue, 24 Oct 2000 14:46:46 +0300

Hi,

>redirection rules.  When a UA gets a 3xx response, it issues a new >request. MUST that new request belong to the same call leg as the >original request?

It doesn't have to belong to the same call leg. It MAY do so, but you
MAY also change the To header (with the new value in the 3xx response
Contact header), and you MAY also change the Call-id value.

And, in any case, it doesn't affect anything else than my own
implementation, even if I use the same Call-id (which one would probably
do). 
I mean - I don't even have to issue a new INVITE when I receive a 3xx,
so any possible intermediate SIP proxy etc. should not be affected.

Regards,

Christer Holmberg
Ericsson Finland

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From: "Hisham Khartabil" <[email-masked]>
Date: Tue, 24 Oct 2000 14:53:40 +0300

I can't find in the bis where it says that they belong to the same call leg,
but in section 1.4.4 the last paragraph, it does say "The caller issues a
new request,
with the same call-ID but a higher CSeq, to the address returned by the
first server"

Hisham

-----Original Message-----
From: Christer Holmberg [mailto:[email-masked]]
Sent: 24. lokakuuta 2000 14:47
To: [email-masked]
Cc: Hisham Khartabil
Subject: Re: [SIP] Redirect server returning new From header

Hi,

>redirection rules.  When a UA gets a 3xx response, it issues a new
>request. MUST that new request belong to the same call leg as the >original
request?

Regards,

Christer Holmberg
Ericsson Finland

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From: Christer Holmberg <[email-masked]>
Date: Tue, 24 Oct 2000 15:02:11 +0300

Hi,

Well, you may use the same call-ID value (the value should be unique for
the call, not for a single call leg), but you are still allowed to
change the To- and From headers.

And, chapter 7.3.3. says that the call-ID value can also be changed.

Regards,

Christer Holmberg
Ericsson Finland

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From: Sean Olson <[email-masked]>
Date: Tue, 24 Oct 2000 10:41:19 +0200

Regards,
Sean