PURPOSE: To surely realize destination of call transfer destination at a low cost by setting and informing subscriber configuration information of a call transfer destination to a destination ISDN communication equipment and a subscriber ISDN communication equipment of a transfer destination during communication by a prescribed ISDN communication procedure.

CONSTITUTION: A system control section 29 is provided with a CPU, a ROM and a RAM or the like, a program for subscriber configuration information transmission notice processing, priority call processing and subscriber configuration information transmission service processing is stored in the ROM, registration telephone number information called by its own equipment, subscriber configuration information such as terminal equipment information of each ISDN communication equipment and call priority by destination are set and stored in the RAM, the subscriber configuration information transmission notice processing and the priority call processing and the subscriber configuration information transmission service processing or the like are executed according to the program.