After an IOS upgrade from 12.3 to 12.4T we have started to get random busy signals when trying to call from one site to another (but not the other way around).
I know very little about VoIP and need some help on what diagnostics to run and what to look for.
Each site has a PBX that terminates into the 2811, a very simple set of dialing rules on each 2811 then forwards VoIP traffic to the second site or the local PBX (NEC I think).
After an upgrade of the IOS and the implementation of some QoS rules, there are random busy signals when trying to phone from one site to the other. The most number of calls I have seen is 3-4 and there was no CAC limit programmed in (though I did try put in one at 7 just to check).
Any help would be appreciated.