Subject: [Sip] Providing Delayed Call Information

From: David Benoit <[email-masked]>
Date: Thu, 26 Jan 2006 11:41:23 -0400

Cross posting this as it may be more applicable here.

----- Forwarded message from David Benoit <[email-masked]> -----

Date:	Tue, 24 Jan 2006 16:49:00 -0400
From:	David Benoit <[email-masked]>
To:	[email-masked]
Subject: [Sip-implementors] Providing Delayed Call Information

Hi,

I want to solve the following problem.  A large number of the calls that
we get from our providers have all the calling information present
(i.e. the name of the caller, or CNAM if you wish), but some of the calls
don't have that present.  We have several alternative sources for calling
name information that we consult to populate that name (caches, databases,
etc.) but that lookup can take "time" (not a long time, but not
instantaneous).

The problem is, I don't want to hold back the INVITE until I get that
information back; it could take like 100ms or so depending on the source
and I am not willing to wait.  I want to send out the INVITE to the UAC
and when the calling name information has been determined, send that to
update the information that was in the INVITE.  As an example, for any of
you Q.931/850 types out there, it would be the same as getting the Setup
message without a calling name and getting a Facility message sometime
later on with that name.

I initially thought that the UPDATE method was what I wanted, but after
actually reading the RFC, it's not at all what I want.  I then thought
that I wanted an INVITE/Replaces, but that seems to me like using a
sledgehammer to hang a picture :)  and I'm not really sure it would have
the desired effect.

So, I need to know if this is already "handled" in SIP.  I can't find
anything that suggests how to do this and even though I could add support
in our systems for a custom method that would allow this, I would rather
not if the problem has already been solved.

Suggestions?   Thanks in advance!

David
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---

From: "Kasturi Narayanan" <[email-masked]>
Date: Thu, 26 Jan 2006 13:26:43 -0600

David,

If the intention is to provide the identity (name) to the called party, so
that it can be used to take a decision whether to answer the call or not etc
then it needs to be included in the Invite message.

And BTW in the Traditional PSTN world the called party is not alerted until
the caller-id info (name) is fetched from the LIDB database.

So withholding an Invite and launching a Query to get the name is not a Bad
idea. 
At the same time the caller can be returned a 100 trying or a provisional
response equilvalent to Call-Proceeding  (without SDP even when PRACK is
enabled and Invite is received w/o SDP ).

This way the UAC can be satisfied not to Retransmit and at the same time if
the UAC also can be enabled to  play a local call-setup tone to satisfy the
caller's ear.  

Kasturi

-----Original Message-----
From: [email-masked] [mailto:[email-masked]] On Behalf Of David
Benoit
Sent: Thursday, January 26, 2006 9:41 AM
To: [email-masked]
Subject: [Sip] Providing Delayed Call Information

----- Forwarded message from David Benoit <[email-masked]> -----

Hi,

David