I have some 7921 phones and 15 1240 AP's in two adjacent warehouses. All had been working fine (no complaints from users) for over a year. Recently, every phone drops connectivity occassionally. Ping from the AP to the phones shows very high latency: over 1000ms. But pings to wireless data scanners associated with the same AP are good: around 50ms. No vlans separate the data and voice. The ping latency happens even when only one 7921 is associated with the AP. So I suspect the firmware issue.
I upgraded the phone firmware from factory default to CP7921G-1.2.1.LOADS. But this did not solve the problem.
Thanks in advance.
To clear up the ping latency question, the 7921/7925 phone utliizes power save and if proxy ARP is enabled, it doesn't have to wake up for each DTIM, so could see around 800ms of delay if the phone is not on a phone call.
If you want to use ping for latency tests, then ensure that the phone is on a call, then ping the phone.