One of my clients is having a problem that is proving very difficult to track down. They have an inhouse VoIP solution using Cisco UC540 and SPA525G2 phones. The switch is a Cisco Cmall Business SF 300 48 port for PoE. The problem is that phones randomly reset dropping any active calls. They do not seem to reboot however from a power issue considering the phone reboot history is not showing the events and their uptime shows months since the last reboot. The power consumption on the switch is well below concerning and shows no errors. What does happen is that the phone re-registers. Here is a snippet of the log from the UC540 right after one such event:
13339: Jan 8 18:54:40.286: %IPPHONE-6-REG_ALARM: Name=SEP708105B39B90 Load=7.5.1a Last=Hard+Unknown
013340: Jan 8 18:54:40.598: %IPPHONE-6-UNREGISTER_ABNO
RMAL: ephone-4:SEP708105B39B90 IP:10.1.1.15 Socket:20 DeviceType:Phone has unregistered abnormally.
013341: Jan 8 18:54:40.598: %IPPHONE-6-REGISTER: ephone-4:SEP708105B39B90 IP:10.1.1.15 Socket:13 DeviceType:Phone has registered.
013344: Jan 8 18:55:52.418: %IPPHONE-6-REG_ALARM: Name=SEP708105B39D50 Load=7.5.1a Last=Hard+Unknown
013345: Jan 8 18:55:52.626: %IPPHONE-6-UNREGISTER_ABNO
RMAL: ephone-18:SEP708105B39D50 IP:10.1.1.20 Socket:10 DeviceType:Phone has unregistered abnormally.
I am really getting heat to address the issue but I don't have much more to go on than this log. The frustrating thing is that it happens randomly and it normally is just one phone at a time. I have found one similar post about disabling proxy arp on our firewall (ASA 5505) which I am tempted to do but I am not sure if this will affect our NAT or ACLs on the firewall.
Anyone have any possible solutions or leads?