Three network fused set top box

The invention is suitable for the field of communication and discloses a three network fused set top box which comprises a central processor, a router, a network television module, a video interface, an audio interface, a terminal signaling platform, I/O (Input-Output) interface, and a switch unit, a telephone line circuit module, IP network circuit module and telephone circuit module connected to the central processor. The three network fused set top box can establish two-way call connections with a network television operating terminal, an internetwork service operating terminal and a voice communication operating terminal in a three network fused system for communicating through the terminal signaling platform. The three network fused set top box not only can realize a network television function, a network voice communication function and various internetwork service functions based on the three network fused system, but also can realize a traditional digital television function and a two-way telephone communication function of a PSTN (Public Switched Telephone Network) fixed-line telephone terminal/mobile telephone terminal outside the three network fused system, thereby realizing the fusing of various business functions.