Hello I have 3 IP Phones 7912G, which work on SCCP, which suddenly present the next simptoms: the Hold button is red the Meniu button is green and the display of the phone is blank and shows nothing. The switch port still function. The phones arent register with CallManager. These simptoms arent described in cisco documentation. If someone have some documentation, ideas or useful links please give me. Thank you very much for your time.