Patent ID: 7944911
Filing Date: 2011-05-17
Classification: H04M

Abstract:
1. A network device having a plurality of telephones each connected thereto over a public network or an Internet network or directly, comprising: a switch unit for switching where to connect a first telephone of said plurality of telephones between said public network and said Internet network, said first telephone being connected directly to the network device; and a power supply unit for supplying said switch unit with an operating voltage for operating said switch unit, wherein: said power supply unit is capable of supplying said operating voltage for a predetermined period of time as counted from when a device operating voltage supplied to operate the network device is no longer supplied; of said plurality of telephones, a second telephone is connected over said public network to the network device; of said plurality of telephones, a third telephone is an Internet telephone; and said switch unit includes an erroneous connection prevention unit preventing said first and second telephones from becoming communicable with each other when said second and third telephones are communicable with each other and the network device is no longer supplied with said device operating voltage.