7841 IP Phone loses power only during calls (Not physical)

[Bryson F]

Hello all, 

first thing first, i have checked everything possible with its physical connections except changing it to a different location and testing.

So i have a 7841 IP Phone connected to a C9200-48P. I have enabled on the phones interface "log event power-inline-status"

but when ever i do a show log there is never any history of even the switch granting power to the phone or even the interface going down. can i have some help to point me in the right direction? it is for our finances/payroll office and id like to help out since they pay us haha.

also i havent checked anything under the CCM yet i dont think i would need to in this situation. 

and i need to determine if this is just one of those weird situations where it would just be best to replace the phone rather than spending too much time on it

Thanks for any help 

[Marcelo Oliveira da Silva]

Hello Bryson

Yes, I would advise you to try connect this phone directly on the switchport and test few moments or on another ethernet port that you know that works fine.

[Bryson F]

@Marcelo Oliveira da Silva 

My only issue with that is since it is a financial managers phone i cannot take it away from their desk with out a replacement and the issue is so sporadic and inconsistent it only happens once or twice every other day. so to rightfully test it may take a few days. would you happen to know any other commands to help monitor this situation with log output? ive asked him to try and keep an estimate log as well so i can see if the time stamps match up. 

[Marcelo Oliveira da Silva · Accepted solution]

Bryson,

I understand how difficult it is to try diagnose intermittent issues, especially from some users.
I assume this phone is being powered by POE and there is no external power supply, correct?

Try configuring syslog on the switch and monitor the port used by the phone. You can check when a port shutdown when sending logs to some software that stores those logs. Other useful information like POE and ethernet port errors may be helpful when troubleshotting.

Days ago I got a issue where the problem was the ethernet connector of the phone itself and it turned off when I pull the cable.

If you use an external power source, use a UPS or replace a telephone power supply that you use frequently and watch if you got any issues.

[Bryson F]

Yes it is poe, i was able to go in after hours and move some ports around and made free space for an extra port for his phone. when i inspected his phone his ethernet port was a little loose but i sat there and moved it around as much as possible but it never lost any power but just for good measure i reran the cable as well so i will monitor it a while longer. but something that is peculiar when he makes calls to a specific IP phone and that call almost always causes the phone to power off which it is also strange because they are in the same switch stack. but every other call seems fine 

[Marcelo Oliveira da Silva]

You can try to check poe power consumption with sh power inline and verify if there is any issue

Power consumption for 7841 is about 3.7W (maybe little less when display turns off).

Module Available Used Remaining
(Watts) (Watts) (Watts)
------ --------- -------- ---------
1 370.0 197.7 172.3
Interface Admin Oper Power Device Class Max
(Watts)
--------- ------ ---------- ------- ------------------- ----- ----
Gi1/0/1 auto off 0.0 n/a n/a 30.0
Gi1/0/2 auto off 0.0 n/a n/a 30.0
Gi1/0/3 auto on 3.7 IP Phone 7841 1 30.0

Let us know your progress on this troubleshooting

regards

[Bryson F]

Gi2/0/25 auto on 3.3 IP Phone 7821 1 30.0
Gi2/0/26 auto on 3.3 IP Phone 7821 1 30.0
Gi2/0/27 auto on 6.5 IP Phone 8841 2 30.0
Gi2/0/28 auto on 3.3 IP Phone 7821 1 30.0
Gi2/0/29 auto on 3.7 IP Phone 7841 1 30.0
Gi2/0/30 auto off 0.0 n/a n/a 30.0
Gi2/0/31 auto off 0.0 n/a n/a 30.0
Gi2/0/32 auto on 3.7 IP Phone 7841 1 30.0
Gi2/0/33 auto off 0.0 n/a n/a 30.0
Gi2/0/34 auto off 0.0 n/a n/a 30.0

The culprit is on g2/0/32 ive monitored it as often as i can with in reason. but i know this switch is no where near strained with power output. It may just be because the phone has aged. But i am a new network admin for this company and i havent been able to find documentation of when it was installed.