[cisco-voip] SIP REFER problems

[Jeffrey Ollie]

I have a CM 5.1.3 cluster connected to an Asterisk 1.4 server via a
SIP trunk.  Calls come into the Call Manager cluster over PRIs and T1
CAS trunks connected to 3700 and 3800 routers.  The routers talk MGCP
to the CM cluster.  The CM cluster sends the calls to Asterisk over a
SIP trunk.  The Asterisk server plays some menus for the caller,
collects DTMF digits and then is supposed to transfer the caller to
other extensions in the CM cluster using SIP REFER.  It was working
Friday when I left work, however today it isn't. CM seems to be
returning a 404 SIP response to Asterisk now.  I'm pretty sure no
changes were made over the weekend, and so far all of the tinkering
I've done hasn't helped (I've even reset the CM service on the
subscriber, I can't do a full reboot of the cluster until tonight).
Google searches and searches of Cisco's web site haven't turned up
anything useful so far.  Regular calls from the Asterisk server to the
CM cluster work fine, it's only when Asterisk tries to transfer an
incoming call do I get the 404.

Can anyone shed any light on my problem?

Jeff