TERMINAL ADAPTER

PROBLEM TO BE SOLVED: To avoid a call loss of an incoming call in the case of this call cannot be received because of internal circumstances at the time of incoming with respect to terminal adapters organized with a representative number. SOLUTION: A controller 5 is connected to adapters 2... through a communication line 6, and ISDN numbers 25 to which adapters 2... are connected, transmission capability information of R points indicating the connection points to terminals, lower layer consistency information, and higher layer consistency information are reported to and held in the controller 5 at the time of the change of their contents or the start of adapters 2... When the adapter 2 which receives the incoming call cannot respond, these information included in the incoming call are reported to the controller 5, and the controller 5 retrieves the adapter 2, which can terminate the call, based on held information and reports the corresponding ISDN line number 25 to the adapter 2 which received the incoming call, and a switching network is requested to transfer the incoming call to the adapter 2 having this ISDN line number.