Subject: RE: [Sipping] Is CONTACT header mandatory in all INVITES

From: Robert Sparks <[email-masked]>
Date: Tue, 29 Jan 2002 11:29:34 -0500

>From: Doug Hurtig [mailto:[email-masked]]
>Hi, 
>  Would like to verify that a Contact header must be present in all
invites, 
>  including mid-call invites. 

Yes, with the caveat below

>  If not true, when is a Contact headr optional in an INVITE message? 

A 2543 implementation might not provide a contact, so you might _receive_
an INVITE (or a 200 to an INVITE) without a contact.

>  If this is true should the saved RouteSet be updated each time a new
INVITE 
>  is received? 

Only the last element, and then only with a value provided in a contact
header.
Any Record-Route values in re-INVITEs are normally ignored.

>  Did see in section 12.2.1.1 the following: "However, requests that are 
>  not refresh requests do not affect the route set for the dialog". 
>  What is a refresh request? 

ReINVITEs for an INVITE dialog, reSUBSCRIBEs for a SUBSCRIBE dialog.

RjS

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---

From: Jonathan Rosenberg <[email-masked]>
Date: Wed, 30 Jan 2002 01:28:54 -0500

Robert Sparks wrote:

> ReINVITEs for an INVITE dialog, reSUBSCRIBEs for a SUBSCRIBE dialog.

This is indicated explicitly in lines 1887-1891 of pdf/ps, which is
section 12.2

-Jonathan R.

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