I've recently come across a rather strange problem with connecting 7937 conference phones to our 3750 switches.
I connected it to port 48 on a switch and it powered on fine. However, if I connected it to another random port on the same switch nothing happened. I tried several other ports and it was the same affect. I tried using a different network cable and even a different 7937 but the result is the same - no power. The result is even the same on a different stack of 3750s.
On the port it does work on I can see it consumes 10.5 watts and the port has a capacity of 15 watts. So it's not overloading the ports. The switches I've been testing with have less than a dozen POE devices connected so the switch isn't overloaded either.
Does anyone have any ideas why a 7937 would power up in some ports and not others?