CUCM - Transfer stopped working

[Tyson Villeneuve]

Hi there. We're running CUCM 9.1.1 with SCCP phones, and transfer has stopped working.

We've tried this from several phones, and get the same result. A user can hit the transfer key to put the caller on hold, dial and connect to the number to be transferred to, and hit the transfer key again. To the user, it seems like the transfer went fine, but the caller just hears a fast busy and isn't connected.

Users are able to put callers on hold without issue, and the conference function works fine, so this doesn't seem to be an MTP issue. Also, this happens with internal and external numbers.

Any idea what I can check next?

[Manish Gogna]

Hi Tyson,

Try restarting the IP Voice Media streaming app service first and check if all MTP's are registered. If the issue persists then collect detailed callmanager service traces for a test transfer scenario involving  only the internal IP phones.

HTH

Manish

[Tyson Villeneuve]

Turns out it was our MLPP:

https://tools.cisco.com/bugsearch/bug/CSCul36221/?reffering_site=dumpcr

Can anyone out there explain the difference between MLPP maximum bandwidth enforcement Lenient and Strict? I'm searching and searching, and all I can find it this:

"When the value for the Locations-based Maximum Bandwidth Enforcement Level for MLPP Calls service parameter is changed from Lenient to Strict, the result could be more calls than the maximum bandwidth that is allowed. However, Cisco Unified Communications Manager does not immediately preempt calls to bring the bandwidth within the allowed budget, but rather, when new bandwidth is requested for the same type of audio or video call. When the preemption occurs, one possible result is a large amount of difference between bandwidth usage and the maximum allowed". 

That doesn't really tell me anything about it...

[Andrew West]

So you are saying even DN to DN (internal transfers) fail also? 

Have you gone through your logging any in RTMT?

[Tyson Villeneuve]

DN to DN fail as well. Restarting media streaming app didn't help.

Which logging options would catch something like this under Serviceability > Logging?