A networking apparatus including a PBX that relays between and manages IP and analog telephones that are assigned extension number information has: a VoIP conversion portion which converts an analog audio signal into an IP signal; an IP connection portion to which an IP telephone is connected; and an analog connection portion to which an analog telephone is connected. When a call originated from an IP or analog telephone is relayed and connected to an analog telephone, extension number information of the call originator is output to the analog telephone.