Is it possible for a switch to kill a phone?

[macsolutions]

I know it may be a strange question, but I'm at a loss for answers.

The customer has one phone on a switch port (of many phones and many switch ports). The phone died.

We configured a new phone here at my office and confirmed that it worked.

Took it to the customer, and it lasted less than 10 seconds on their network. After its supposed death, we swapped locations, cables, switch ports, and even plugged directly into the switch, and yes, the phone really is dead. Won't power on even with a power adaptor.

Is this a wiring problem (the wiring guys say no, they tested), a patch panel problem, or a switch problem?

[BrandonS · Accepted solution]

That is an interesting one.  I don't think there is really a way to know for sure, but I think there are three possibilities:

- Wiring issue

- Switchport issue

- Bad luck two phones died 

I suppose you need to try a third phone regardless so what I would do is plug the third new phone into a known working location that already has the same model or similar phone working to confirm it works there for some hours or days before trying to move it back to the desired location.  And actually if you get this far, I would first move the new phone to the desired switch port directly and only after seeing it work for some time there then move it back to the location at the end of the wiring.  This way if the phone dies again you should be able to determine at what step it was damaged.  I feel like the most likely reason would be a cable or jack showed or similar.  How well did the cable people test?  Ideally they would test end to end with a Fluke or similar quality tester and provide a report.

Good luck.

[macsolutions]

I purchased a POE tester to take to the location to test the port as well. Thank you for these ideas.

[RomanMD]

I'll second Brandon's opinion.

One more thing that I've observed over the time - the old Cisco phones did not like to be plugged into PoE and have also the external power adapter.

Other than that, the wiring guys may buy a PoE tester, they're absolutely not cheap... but may identify problems without killing just another phone...