Abstract: The present invention provides a telephone system for allowing access to both a public telephone network and a computer communication network. The telephone system comprises a telephone line signal processing section adapted to be connected with a telephone network to achieve voice communication via the telephone network, and a telephonic function section including a voice input section, a voice output section, an input key section, and an on-hook/off-hook operation section. The telephone system further includes a VoIP engine section adapted to be connected with a computer communication network to achieve voice communication via the computer communication network, and a switching section for switchingly connecting the telephonic function section with either one of the telephone line signal processing section and the VoIP engine section.