Abstract: There is disclosed a network telephone system which registers subscriber information necessary to monitor a call upon a request for call transfer by a first subscriber who has made dial-up connection, notifies the first subscriber that there is an incoming call from a second subscriber, and makes a call setup for voice in accordance with an instruction from the first subscriber.

Abstract: A virtual AN switch comprises a virtual AN unit. The virtual AN unit is implemented by virtually building the same capability as that of a normal access network device into a virtual AN switch, and is connected to a control switch via a V5.2 interface. Whether or not a subscriber accommodated by the virtual AN switch is accommodated in the virtual AN unit is registered to a subscriber data memory for each subscriber. The virtual AN unit performs a conversion between an intra-office signal and a V5.2 signal message. For the subscriber accommodated by the virtual AN unit, the virtual AN switch serves as a remote accommodating device of the control switch.