Check the POE on the switch. If you have an edge switch the phone is plugged into, you could be maxing out on POE power on the switch. Technically, you can not fill a 48 port switch to the max with 48 7975 phones. There is not enough POE power for all those phones.
You could also simply have a bad port on the switch. Trying moving it to another switch or another port.
I dont have the command in front of me to check the status of POE or power, but do a show /? and find POE I believe. (Or status of switch)
But if you have 48 ports all filled with phones and using POE, the could be losing power.
Also, sometimes when a phone has issues with switchport negotiations, they will randomly reboot. IE... phone is auto and switch port is set to 100 Full, etc.
Also check the patch cables. Bad cables, could = bad POE power to the phone.
