Re: [Sip] Reuse of Sip Call-Id question...

[Martin Larochelle <martin at macadamian.com>]

This is right, although it does not mean that each call attempt must use a new call-id.

You wrote that "We have customer UAs that are reusing the same Sip Call-Id for multiple call attempts into our network.", if by attempt, you mean trying to make a call that fails with a error that can be retried (as 407, 422) then in that case, it is acceptable to use the same call-id ( with an incremented C-Seq and empty to-tag)

--
Martin Larochelle
Software Architect

On Fri, Jun 5, 2009 at 11:15 AM, Attila Sipos <attila.sipos at vegastream.com> wrote:

you will get the same response here as on sip-core.

 

SIP call-id should be unique for each call, it cannot be re-used

 

Regards,

Attila

 

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From: sip-bounces at ietf.org [mailto:sip-bounces at ietf.org] On Behalf Of Cahall, Glenn
Sent: 04 June 2009 17:46
To: chogg at nortelnetworks.com; jdrosen at dynamicsoft.com; zmolek at avaya.com; Marie-Noelle.Mathieu at compaq.com; sip at ietf.org
Subject: [Sip] Reuse of Sip Call-Id question...

Folks,

I work for a VoIP company, Level3 Communications, and have been doing some research on the internet about

a specific condition that has arisen here dealing with the Sip protocol.  Your names came up during my research.

Was hoping I could get some feedback about the reuse of Sip Call-Id.

We have customer UAs that are reusing the same Sip Call-Id for multiple call attempts into our network. 

After reviewing the Sip RFC 3261, both myself and my team concluded that this was a clear violation of the spec.  based

on the following verbiage...

8.1.1.4 Call-ID

   The Call-ID header field acts as a unique identifier to group

   together a series of messages.  It MUST be the same for all requests

   and responses sent by either UA in a dialog.  It SHOULD be the same

   in each registration from a UA.

   In a new request created by a UAC outside of any dialog, the Call-ID

   header field MUST be selected by the UAC as a globally unique

   identifier over space and time unless overridden by method-specific

   behavior.  All SIP UAs must have a means to guarantee that the Call-

   ID header fields they produce will not be inadvertently generated by

   any other UA.  Note that when requests are retried after certain

However, some voice engineers are stating that the definition of “globally unique over time and space”  means only during the

context of a given call.  Therefore, once this context is over....Sip Call-Id can in fact be reused in the very next context.

What is your take on this?

Thanks,

Glenn E. Cahall

Sr. Architect

Level3 Communications

.

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