Subject: SIP Voice mail

From: Marc Petit-Huguenin <[email-masked]>
Date: Thu, 13 Jan 2000 09:42:33 +0000

-- 
Marc Petit-Huguenin
Home: mailto:[email-masked]
Work: mailto:[email-masked]
"Everything I love is either immoral, illegal or makes you fat"

---

From: Marc Petit-Huguenin <[email-masked]>
Date: Thu, 13 Jan 2000 11:02:09 +0000

Hi all,

Sorry for the previous empty message. 

I have some questions/propositions about SIP voice mail. 

I find some information about Voice mail implementation in: 
 http://www.cs.columbia.edu/~hgs/papers/Schu9802_Signaling.ps.gz
 http://www.cs.columbia.edu/~hgs/sip/drafts/requirements.pdf

but I have two problems:

The first problem is for the Voice-mail to choose the correct mailbox. 
If a SIP entity makes a direct connection to a voicemail, the voice mail
can use the From header to select the mailbox (In this case, the SIP
entity is the owner of the mailbox and is connected in administrative
mode, for retrieving messages or configure his mail box). The voice mail
asks for PIN code or rejects with 407.
But if the connection is an indirect connection, the voice mail do not
known how to select the mailbox:

Imagine A and B are UA SIP and V is the SIP voicemail for B.
A calls B (perhaps through a proxy) then a forwarding rule on B
redirects A to V. V do not know that the call was forwarded by B so it
cannot directly connect A to the mailbox of B.

One solution for B is to act as a SIP proxy for this call. V can check
the first Via header (or best, the first Record-Route), and deduce the
correct mailbox from this information.

Another solution is to add a token in the SIP address returned in the
Contact field of the 302:
 Contact: <sip:[email-masked];com.8x8.redirect="[email-masked]">

(I am not sure that a SIP entity have the obligation to keep all the
tokens)

My second problem is to notify a SIP entity that new voicemails are
arrived.

A solution is to use the register method to convey this information. My
email are checked every 10 minutes, so we can imagine that if a SIP UA
registers each 10 minutes, the mailbox informations can be send in the
200 response:

SIP/2.0 200 OK
Via: SIP/2.0/UDP 192.168.0.36:5060
From: sip:[email-masked]
To: sip:[email-masked]
Call-Id: [email-masked]
CSeq: 523 INVITE
Voice-Mail: true;new=5;urgent=0;archived=0

The problem is that we must have a link between the register server and
the voice-mail.

Any comments?

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From: Jonathan Rosenberg <[email-masked]>
Date: Thu, 13 Jan 2000 10:44:20 -0500

> cannot directly connect A to the mailbox of B.

The problem is that you are trying to address the mailbox indirectly.
Rather, a voice mailbox is identified by an address, for example:

sip:[email-masked]

or even:

sip:[email-masked]

In the latter case, the user might be prompted for a pin or password to
identify whose mailbox is being accessed.

So, in your example, B would redirect A to sip:[email-masked].
It works fine in this case.

> The problem is that we must have a link between the register server and

I happen to dislike using SIP for voicemail notifications, particularly
in this way. The reason is that voicemail is a separate service, very
possibly provided by a provider that is not by SIP proxy/registrar
service. Therefore, linking these together won't work for separate
providers. I don't want to rule that case out. I personally like IMAP;
this allows for unified notifications of both email and voice. 

-Jonathan R.
-- 
Jonathan D. Rosenberg                       200 Executive Drive
Chief Scientist                             Suite 120 
dynamicsoft                                 West Orange, NJ 07052
[email-masked]                     FAX:   (732) 741-4778
http://www.cs.columbia.edu/~jdrosen         PHONE: (732) 741-7244
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