Subject: [Sip] 491 issues

From: Christer Holmberg <[email-masked]>
Date: Wed, 20 Feb 2002 12:59:23 +0200

Hi,

A couple of small issues on 491 Request pending.

1.

Chapter 14.2 defines that a node receiving an INVITE shall return 491 if
it has a pending INVITE transaction in progress for the same dialog.

Chapter 25.4.27, however, says that 491 shall be returned for any
received request if the node has a pending request (the text doesn't
even mention if the request methods are the same or not) within the same
dialog. I think it shall be more clarified that 491 shall be returned
only in the case of INVITE requests (and any other request where there
may be a functional race condition). For example, if a node receives
INFO, and has a pending INFO within the same dialog, there may be no
need to return 491...

2.

This is just to clarify.

If a node sends an INVITE request, it may by a proxy be looped back to
the same node. However, even if the Call-ID is the same, but the local-
and remote tags are different for the incoming and outgoing INVITE, they
will represent different dialogs, and there is no risk a 491 would be
returned for the incoming INVITE. Correct?

Regards,

Christer Holmberg
Ericsson Finland

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