Provided is a method of automatically detecting an end node behind a phone on a computer network. Media access control (MAC) address of an end node is determined, wherein the end node is coupled to a phone and the phone is coupled to a switch on a computer network. It is also determined whether the MAC address of the end node is recognized on a port of a switch on the computer network. If the MAC address is recognized on a port of a switch, a list of MAC addresses recognized on the port is obtained. If the list has two MAC addresses, the MAC address of the end node from one of the two MAC addresses is determined.