asterisk users - Mar 2004 - [OT] PoE (Power over Ethernet) for 7940G

I have a few 7940G phones on a LAN hub, and I'm looking at the 3COM 
3CNJPSE power injector.  Can I put one of these behind my LAN hub and 
power all the phones, or do I need one for each phone?

 From the spec, it looks like PoE tries to discover whether a device is 
powered over ethernet.  Can I just put 48VDC on pins 7-8?  Will my 
Netgear pass this through to the phones?

Thanks,

-- 
Michael Welter
Introspect Consulting, Inc.
Denver, Colorado
+1 303 674 2575
mike@introspect.com
www.introspect.com

Michael Welter wrote:
> I have a few 7940G phones on a LAN hub, and I'm looking at the 3COM 
> 3CNJPSE power injector.  Can I put one of these behind my LAN hub and 
> power all the phones, or do I need one for each phone?
> 
>  From the spec, it looks like PoE tries to discover whether a device is 
> powered over ethernet.  Can I just put 48VDC on pins 7-8?  Will my 
> Netgear pass this through to the phones?
> 
> Thanks,
> 
Any power injector must be between the device it's powering and any 
other device.

Phone----Power Injector-----switch/hub.

Michael Welter wrote:
> I have a few 7940G phones on a LAN hub, and I'm looking at the 3COM
> 3CNJPSE power injector.  Can I put one of these behind my LAN hub and
> power all the phones, or do I need one for each phone?
> 
>  From the spec, it looks like PoE tries to discover whether a device
> is powered over ethernet.  Can I just put 48VDC on pins 7-8?  Will my
> Netgear pass this through to the phones?
> 
> Thanks,
If you do this, please have a battery powered video camera ready, I want to
see it!

No offense intended, honest.

A friend of mine insists that if you hook up the power to a floppy drive
backwards it creates this nice little poof of blue smoke.

-----
Andrew Thompson
http://aktzero.com/