CUCM 7.1(5) with only one server, MRG, MRGL, Device Pools and Regions correctly configured. No MoH is heard (like muted) when a phone is put on hold. This happens with internal as well as external calls.
No multicast MoH is configured, no strange things.
When an external call is put on hold, the output of "show call active voice compact" command on voice gateway shows external number connected to ip address 0.0.0.0.
When an internal call is put on hold, on the phone which is no hold you don't see any
CUCM Reload does not help.
Which codec are you using?
Is the MOH server registered?
Do you see any errors in the app log?
If this helps, please rate
Sorry my issue report was wrong since MoH worked just fine internally. Looking up at TAC Case Collection we found a workaround for a mysterious bug, that is to set MTP Required on the H.323 Gateway configuration. That solved the issue.
FYI it's a bug in recent Cisco ISR Routers firmware which prevents unicats MOH from being played back when "ip cef" is enabled on the reouter. Disabling it makes the MOH work without the need of an MTP in the Device Gateway configuration.
Disabling "ip cef" is generally not a good idea.
There is an alternative solution for this.
Please enable "Duplex Streaming" service parameter in CUCM which should solve this issue without disabling CEF in ISR routers.
I just fixed this issue right now by enabling Duplex Streaming. It worked great. The phones do not get reset. The only other option is to upgrade the code on your gateways.