I am trying to get a 5310 Conference unit to connect to a 5220 IP phone. I have tried this several times with no luck. Normally I would suspect that the Conference Sidecar is bad but when I connected it to a 5020 it worked fine. The side car is designed for a 5220 therefore will not mount to the 5020. This is not a brand new unit. I am not using POE, I am powering through the transformer plugged into the side car then plugging the side car into the power port of the 5220. Any suggestions? Also should I be able to connect a Plantronics headset to the headset port to test the port.