I have a network with CCM 4.2, IP phone 7920 and AP 1131AG.
All phones are registered to CCM. When the phone does to standby mode I try to make a call, from another phone I get the 3 or 4 ring back, but the destination phone does not ring. After that I get busy tone. Then if I try a second call I get immediately busy tone! The third call will get success. It seems the phone does not wake on time to get the call.
The ping to the phone have an answer from 30/40 ms to 1400/1500 ms. After while the phone does not respond to ping, is in this situation the problem happen, the phones does not ring an incoming call.
If I leave the phone stand the problem happens again.
Is this a bug? I have the latest load for the phone and last IOS for the AP.
Is there any workaround? If it's necessary can I configure the phone to be always on active mode?