I got one 9621G to do some testing with since the refurb market of 4621s is drying up. For testing I tried an Avaya power injector but it doesn't power up. When I plug it into a POE switch it does power up. I plug a 4621 into the power injector and it works. The POE switch says it is drawing 7 watts on a port with 15.4 max and it is a class 2 device. Does anyone know what the difference is?