I have a CCM 4.1.3sr4d cluster comprising of 2 servers (1 Pub and 1 Sub). We have 10 remote sites all using 28xx series routers and all end users use 794x, 796x, 797x or 7985 phones. There are no analog devices other than faxes. G.711 calls are used on LAN environments and G.729 for the calls across the WAN.
The two CCM's are providing the conferencing and transcoding facilities.
After around 32 minutes on a conference call the voice quality drops dramatically, with users reporting it sounds like daleks on the line. After a couple of minutes this issue clears. It appears to affect all users on the conference. It does not seem to matter how many parties are on the call at the time.
Can anyone give me any pointers as to where to start troubleshooting this issue please?