That's so stranger, Recently, we found this problem more than 3 times. when we disconnect the cisco ip phone from 4507 switch, and then connect again, it cannot power on any more, when I connect to 4507 switch, "show power inline" command displayed the port is " Ieee PD" cannot displayed the IP Phone 7945... but when I move the cable to 3750 switch, show power inline command, it dispalyed as IP Phone 7945.
We have the same issue in three 4507 switch, no matter what I change the new cable or new IP phone. doesn't work... I don't if the switch 4507 port have some problem or how to reset the power inline to default. or you may have the same problem before when you deployed the cisco IP phone to your network replace PBX phones.