Tracking Calls with CUCM

[mumbles202]

Just wondering if anyone has a good document to understand how CUCM tracks calls and media streams.  Working on an issue that's just popped up after a CUCM (BE5K) has been in service for years that I'm having some difficulty tracking down.  The gateway is a 2821 w/ 2 PRIs and is MGCP.  User A initiates a call outbound and that call connects and has audio and working normally.  Then a remote user, User B, calls in to check their VM and goes to what should be the hunt pilot for Unity.  User A hears a couple of beeps in their conversation, but otherwise normal.  User B, however, gets joined to the call that User A is on and can hear that conversation.  The call logs from CUCM show the call from User B going to the hunt pilot normally.

This system has been in production for years and the only recent changes (w/in the last 6 months) have been the core switch has been replaced, the internet handoff has been moved to the 2821 using a VRF, and the firewall was RMA'ed for the same model device, just a different firmware revision (the core switch is the gateway for all the phones, CUCM/Unity, and the VG is in the same subnet as the phones).

[Jaime Valencia]

CUCM handles the signaling and tells users to talk to each other under normal circumstances, the RTP doesn't flow through CUCM unless you configured the use of TRP/MTP.

A conference would require the involvement of a CFB to happen, the BIB of the phone is only used for barge.

You would need to look at CUCM traces and possibly a sniffer/logs from the device as well as IPVMS logs, might want to check CUC logs as well, and before any of that, analyze the exact call flow you have on both calls.

[mumbles202]

Thanks for the reply. As far as I understand the signaling should be all CUCM and then the RTP would ge between devices like you pointed out. I should point out that what I detailed was just 1 example. I mentioned CUC as the last report of an issue I had involved it.

At other times a user internally will be on a call to the PSTN and another user either picks up the handset to dial and somehow joins the other call and can hear everyone involved in the conversation. Unfortunately it seems totally random and widespread enough that rhe only effective captures might be SPANing the interface facing CUCM and facing the VG. 

I haven't heard of the issue on calls that are entirely in the office.