An apparatus and corresponding method for managing busy lamp field (hereinafter, referred to as BLF) information in an inter-networking system are provided which are capable of collecting and managing BLF information of every PBX in a BLF information repeater added to the inter-networking system. The BLF information repeater reduces the load of the inter-networking system by transmitting the BLF information to a PBX that requests the BLF information.