[Asterisk-Users] [OT] PoE switch question

[Kevin P. Fleming]

Sean Kennedy wrote:
> http://www.cdw.com/shop/products/default.aspx?EDC=568864
> 
> Can anyone tell me if this switch will be able to supply a Cisco 7940 
> phone with power?  I've heard of PoE issues with differing switches and 
> the like, and I don't know how to check to see if this switch will be 
> able to drive the phone in question.

I would suspect it will not. Cisco phones do not implement standard PoE, 
they are proprietary.

However, when using a "dumb" PoE power supply (like the 3Com brick), a 
simple adapter cable (swapping the pairs for power) works just fine with 
Cisco phones. When using a "smart" PoE power supply that expects the 
device to negotiate with it, the phone won't negotiate properly and 
there's a good chance it won't work.