[cisco-voip] CM 4.1(2) ad-hoc conferencing....

[David]

Greetings,

I'm having an issue where we can't create ad-hoc conferences with
external parties.  By "external" I mean callers sourced from the PSTN.
 Internally (IP phone-to-IP phone), conferencing works fine.  The
problem comes in when we try and add 1, 2 (or more) external parties
to the conference - When we hit the "conf" softkey to conference
everyone together, it immediately drops all of the external parties
but retains the internal parties.  When we hit the question mark on
the phone twice as we're connecting each party, it shows the codec
used as being g.711 for all of them.  I don't know that that's an
issue, but I thought I should mention it.

The way the network is laid out is that there is a central site (where
the CM cluster is) and a remote site.  The sites are connected via
MPLS.  The remote site is the only site that has phones at present -
that is where we're having this problem.  Local transcoding resources
have been configured on the CM.

I know that this is a very open-ended question, and I'm not
necessarily looking for a sure-fire answer, but I'm hoping I can get
pointed in the right direction on where to start troubleshooting.  So
far, In the CM I've tried resetting the MTPs, the conference bridges,
and the "Transcoder" from the "Service --> Media Resources" menu.

Is it possible that the DSPs on the router have locked up or
something?  Would that cause this problem?  I'm rather new to
troubleshooting these kinds of problems, so if you could be somewhat
explicit in your suggestions that would be incredibly helpful and
appreciated.

Thanks much, in advance!