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Wassim Aouadi

ip phones reboot


On our PoE switch, IP phones reboot many times during the day. I checked the switch. It did not reboot.

Is there a way to verify power consumption by phones on the switch?


paolo bevilacqua
Hall of Fame Master

show power inline

Note however that when phones mysteriously reload, that is likely due to broken network connectivity, not power problem.

Cisco Employee


Please check the CUCM server sys log, if the phones are missing 3 hello packets they will re-register, and if there is no secondary server it will look like they are rebooting, if the sys log indicates that the device is rebooting itself then I would setup a sniffer trace to check what is going on, or if you have a monitoring system that might indicate a flapping issue on the network.

Christian Nuche



We have a cluster of two CUCMs. On  RTMT I selected the subscriber. I have System Logs, Applications Logs and Security Logs. Where should I look at, and what type of message should I search for?


check voice and data are on seperate VLAN and not using VLAN 1


What type of POE switch

Switch is WS-C2960-24PC-L model

NSWAGCS01028>sh vers

Cisco IOS Software, C2960 Software (C2960-LANBASEK9-M), Version 12.2(50)SE4, RELEASE SOFTWARE (fc1)

Technical Support:

Copyright (c) 1986-2010 by Cisco Systems, Inc.

Compiled Fri 26-Mar-10 09:14 by prod_rel_team

Image text-base: 0x00003000, data-base: 0x01400000

ROM: Bootstrap program is C2960 boot loader

BOOTLDR: C2960 Boot Loader (C2960-HBOOT-M) Version 12.2(44r)SE4, RELEASE SOFTWARE (fc1)

TNSWAGCS01028 uptime is 2 weeks, 3 days, 22 hours, 11 minutes

System returned to ROM by power-on

System image file is "flash:c2960-lanbasek9-mz.122-50.SE4/c2960-lanbasek9-mz.122-50.SE4.bin"


cisco WS-C2960-24PC-L (PowerPC405) processor (revision E0) with 65536K bytes of memory.

Processor board ID FOC1451X63T

Last reset from power-on

2 Virtual Ethernet interfaces

24 FastEthernet interfaces

2 Gigabit Ethernet interfaces

The password-recovery mechanism is enabled.

64K bytes of flash-simulated non-volatile configuration memory.

Base ethernet MAC Address       : 8C:B6:4F:C6:0C:80

Motherboard assembly number     : 73-11305-09

Power supply part number        : 341-0266-03

Motherboard serial number       : FOC14503Y0C

Power supply serial number      : LIT1448043W

Model revision number           : E0

Motherboard revision number     : A0

Model number                    : WS-C2960-24PC-L

System serial number            : FOC1451X63T

Top Assembly Part Number        : 800-29397-05

Top Assembly Revision Number    : C0

Version ID                      : V04

CLEI Code Number                : COMCS00ARA

Hardware Board Revision Number  : 0x01

Switch Ports Model              SW Version            SW Image

------ ----- -----              ----------            ----------

*    1 26    WS-C2960-24PC-L    12.2(50)SE4           C2960-LANBASEK9-M



Since when the problem started?

is it happening to all phones under 1 switch? how about the others?

Did you experienced call drop and restart while on a call on that phone?

Try the following to further isolate the cause;

- register the phones to the other CUCM and see if that fix the issue.

- try to use static or set the dhcp lease time to infinte.

- Check all switch in between for any error logs

- Since when the problem started?

it started since we installed the branch LAN

is it happening to all phones under 1 switch? how about the others?

it's happening to all phones. Staff says that network applications stop too. I guess there's a switch connectivity problem?

Did you experienced call drop and restart while on a call on that phone?

no. Calls are interrupted.


Application and connected calls should not be affected if there's a problem in CUCM. Continue troubleshooting in the network side.

It's not a CUCM problem. All our ip phones are connected to it and no other calls have been reported as dropped.

How about the PC's not connected to the phones?  Do you see intermittent link failures?  Can you post a "sh logs"?

all PCs are connected behind ip phones.

We are seeing similar behavior. Our cases seem to be triggered by one VoiP connected PC that freezes up. The connected phone will reboot and within minutes, other random phones connected on the switch will begin rebooting. 

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