I have a metwork with 35 AP 1242 (only 2.4ghz band) and 30 7921g.
I'm using a WLC 4404 version 4.2.61 7921G version 1.1.1, CCME version 4.1, AP IOS 123-7JX.
The coverage seems to be good and also the overlap.
The problem is: some times casually and also not walking we lost voice (one way o both way) for 10 or more seconds the call is still active. I tried to improve roaming, I have enable WMM support, DTCP and all the features racomanded on the wlc docs. I have analised RF interfernce with wy-spy and not seems to be relevant interference. The AP profiles are all in pass (if you check on the WLC) I can ping the CCME with a PC on the WiFi VoiceVLAN.
It very stange and a can't find a solution because the problem is not localised in an area. It is more evident when we have a conversation between 2 wifi phones.
I can't find a way to solve the problem.