No power to IP Phone 7940 on Z3

[JackK]

We are testing the Z3 as a small branch office setup.  In testing IP Phone connectivity, when a Cisco IP Phone 7940 is connected to switch port #5, the phone does not receive power.  However, if a Cisco 8845 is connected, it does power up.  Has anyone run into this situation or knows of a solution, please let me know.  I have not connected locally to the appliance and poked around yet.  Perhaps, the PoE version on the 7940 is not compatible with the version on the Z3.

[FM]

Hey, @JackK!

Did you check if the phone powers up with a power injector?

[JackK · Accepted solution]

I did not try a power injector, however, connecting to a Cisco Catalyst 3560 works fine.  Also, a newer 8845 phone does negotiate power and powers up when connected to the Z3.  As PhilipDAth mentioned, this most likely due to the Z3 not supporting the pre-standard Cisco proprietary PoE that is on the 7940.

Thanks for the response.

[PhilipDAth]

I'm going to guess the Z3 only supports standard PoE negotiation.

A 7940 does not support standard PoE negotiation, only the Cisco proprietary pre-standard method (a 7940 is a very old phone ...).