PURPOSE: To realize trunk line telephone and TV intercome communication and to display a prescribed reference information picture on a TV monitor screen by providing TV (television) intercome connection terminals, a television video processing circuit, a television monitor picture display means and a display function means.

CONSTITUTION: A moduler unit 1 as a main device is provided with trunk lines L1 and L2, terminals T1 and T2 for connecting telephone sets on the market, moduler jack insertion terminals MJ1 and MJ2, connection terminals D1 and D2 for the intercome D of a regular type, and connection terminals D3 and D4 for a TV doorphone DTV. Furthermore, CPU 2 with four bits, a power circuit 3 and an intercome call circuit 4 are provided. A video processing circuit 4a for the TV intercome DTV displays a monitor picture on a liquid crystal screen 4C through a driver 4d. CPU 2 is provided with a display function for selectively secreen-displaying plural pieces of reference information on the liquid crystal screen 4C. Thus, a trunk line call and a TV doorphone call are realized by connecting the telephone set on the market.