I am running CME v4.x on a 2821 with an NM-ESW-16. I plug a 7931 phone into one of the switch ports. The 7931 does not power up. I have shut and no shut the port and tried all other ports. I can get a 7941 to power up. Does anyone have any idea if the 7931 can be powered from the NM-ESW-16?