Cisco 8831 Conference Phones POE vs Power Brick?

[dianareyes]

Hello,

I have a Cisco 8831 conference phone that does not Register when powered on POE, phone displays "Phone is UnRegistered".  However when I switch over to the power brick it registers just fine.  So far, I've tried changing locations, perform a factory reset, tried using different cables, changed switch ports, and received the same result.  

It appears this phone does not like POE, has anyone ever come across this issue?   This phone may be under warranty and I'm about to process an RMA, but thought I'd reach out to ensure I've covered/tried everything.  Any suggestions are greatly appreciated!!!

Thanks in advance,

Diana

[Gordon Ross]

We only use 8831s with PoE and have no problems. It could be a faulty phone or a faulty switch. (Not much help, eh?)

GTG

[Zach S · Accepted solution]

Diana,

With the steps you've gone through you've established a few things.
1. The phone works, more or less, it power up and registers with the power brick.
2. The switchport it's connected to has the correct data configuration to let the phone register when it's connected to the brick.

The problem you are having is with PoE.

If you use a different phone in that same location, will it receive power? If that phone power up then the problem is definitely the phone's RJ-45 port, probably a broken lead or something.

If that second phone does not power up, then you should investigate the path, if you have a network tester that can detect broken pairs, you may find that your patching is broken at some point with a wire pair that would have gone unnoticed with data, since PoE rides over the unused wire paris.

Last but not least, do not forget that Cat5/6 cables and PoE have distance limitations, make sure you aren't trying to push PoE over 100 meters.

[dianareyes]

Hi there,

Unfortunately, the site does not have another CP-8831 to test out, however we did take a CP-7937g into the conference room and it registered just fine using POE. It's definitely not the switch port and we did check the power inline on the CP-8831 and it was receiving a 15.4Watts, however will fluctuate and sometimes receive 13Watt, not sure if that's due to current usage, but overall i think this CP-8831 may be broken.    

Thanks for all your help & 411!!!  Appreciate it.

Cheers!