BUILDING CONTROLLER AND INTERPHONE SYSTEM

An interphone system for use in collective housing constituted by a plurality of residential buildings and a centralization building (5) capable of communicating with each residential building, each of the residential buildings comprising: a residential-unit master device (30) installed in each residential unit; a plurality of collective entrance devices (10A-10D) capable of communicating with the residential-unit master device (30); and a building controller communicatively connecting the residential-unit master device (30) in each residential unit with the collective entrance devices (10A-10D) in the building, wherein the building controller has: a building controller ID that, at the time of calling up the residential-unit master device (30) from the centralization building (5) via the building controller, is used for the centralization building (5) to identify the building controller; and a collective entrance device ID that, at the time of calling up the residential-unit master device (30) from the centralization building (5) via the building controller, is used for the residential-unit master device (30) to identify the building controller as a virtual collective entrance device different from the collective entrance devices (10A-10D).