[Asterisk-Users] POE

[Kevin Day]

On Aug 28, 2004, at 1:13 PM, Michael Welter wrote:
>>
>
> Since the Cisco 79XX phones preceded the PoE standard, they are 
> different--polarity is reversed.
>
> IANAE, but as I understand the PoE devices, there are two types--one 
> always applies -48VDC to the brown pair while the other senses (as per 
> the PoE spec.) whether the device at the other end requires power.
>
> I'm not willing to risk a $300 Cisco set, so I'm still using the wall 
> wart.  Is anyone providing LAN power to 79XX phones at a reasonable 
> cost?
>
> Mike
>

I'm using one of these:

http://www.linksys.com/products/product.asp?grid=36&scid=47&prid=582  
(under $40)

This is a "dumb" device that's always powering the ethernet line, but 
it works. The only catch with 7940 and 7960 phones is that they expect 
the polarity to be reversed, compared to the rest of the world's POE 
specs.

So, you either have to make a funky ethernet cable (detailed in the 
Wiki) or cut the cable from the included 48V power supply and reconnect 
it backwards.

Works wonderfully.