I have an IP Phone 7970, connected onto a non-Cisco LAN Switch. After using for a very short period of time, the switch port disable itself. Even I disconnect the IP Phone and plug a normal PC onto that LAN port, it can't be workable again. I've tried on two Switches and get the similar symptom. (The 7970 is powered by Power Adaptor.)
Has anyone got similar symptom in the past? Would it be possible that the electrical power is output from the IP Phone to the LAN Switch via the LAN cord, so that the LAN Switch is damaged?