PURPOSE: To select a transmission control circuit coincident with the transmission control procedure used by a terminal and to perform the communication by transmitting a request to an ISDN exchange network to carry out the communication with the terminal via a channel B connected to the transmission control circuit based on the terminal communication attribute information contained in the call setting signal received from a channel D.

CONSTITUTION: Plural different transmission control procedures are optionally selected based on a table showing the correspondence between the protocol identification information and the incoming subaddress information included in the lower rank layer matching property information contained in the call setting request signal received from a terminal 5 via an ISDN 4 and the number of a channel B included in an ISDN interface 7 set between a communication controller 1 and the ISDN 4. Then the communication of data is attained between the terminal 5 and a CPU 2 in the same transmission control procedure as an incoming terminal. As a result, an electronic computer can perform the communication with the terminal 5 via the ISDN 4 in the same transmission control procedure as the terminal 5 against the call received from the terminal 5.