An intercommunication system which is used in an apartment complex comprising plural residential buildings, each of the residential buildings comprising: room parent devices installed in respective rooms; a terminal device comprising: a call unit configured to enable a call manipulation for calling a visit destination room parent device; a storage unit which is stored with a call table in which room numbers of the rooms are correlated with pieces of room parent device identification information for identification of the room parent devices of the rooms, respectively; a processing unit configured to perform processing of converting a signal that is input to the call unit into the room parent device identification information of a call target room parent device on the basis of the call table; and a transmission unit configured to transmit the room parent device identification information to the room parent devices in the building where the terminal device is installed; and a building control unit configured to connect the terminal device to the room parent devices of the rooms of the building where the building control unit is installed, by an intercom line, wherein: the plural residential buildings are connected to each other by a network in which a communication is performed according to a general-purpose protocol, and wherein: the terminal devices in each building have a common call table, and when the call table of one terminal device amongst the plural residential buildings fails, the call table of the one terminal device amongst the plural residential buildings that has failed is repaired using another call table of another one terminal device amongst the plural residential buildings. room parent devices installed in respective rooms; a terminal device comprising: a call unit configured to enable a call manipulation for calling a visit destination room parent device; a storage unit which is stored with a call table in which room numbers of the rooms are correlated with pieces of room parent device identification information for identification of the room parent devices of the rooms, respectively; a processing unit configured to perform processing of converting a signal that is input to the call unit into the room parent device identification information of a call target room parent device on the basis of the call table; and a transmission unit configured to transmit the room parent device identification information to the room parent devices in the building where the terminal device is installed; and a call unit configured to enable a call manipulation for calling a visit destination room parent device; a storage unit which is stored with a call table in which room numbers of the rooms are correlated with pieces of room parent device identification information for identification of the room parent devices of the rooms, respectively; a processing unit configured to perform processing of converting a signal that is input to the call unit into the room parent device identification information of a call target room parent device on the basis of the call table; and a transmission unit configured to transmit the room parent device identification information to the room parent devices in the building where the terminal device is installed; and a building control unit configured to connect the terminal device to the room parent devices of the rooms of the building where the building control unit is installed, by an intercom line, wherein: the plural residential buildings are connected to each other by a network in which a communication is performed according to a general-purpose protocol, and wherein: the terminal devices in each building have a common call table, and when the call table of one terminal device amongst the plural residential buildings fails, the call table of the one terminal device amongst the plural residential buildings that has failed is repaired using another call table of another one terminal device amongst the plural residential buildings.