PURPOSE: To change definition during the operation of a system by providing an SSAP address dynamic change use interface, SSAP real address dynamic changing means for internal management at the time of session connection and SSAP read address memory holding means after the session connection.

CONSTITUTION: An SSAP read address is calculated by a referring means 4 from a management table 7 to refer an SSAP local ID and a real address and a session connection processing is executed according to a session control protocol by a session connecting means 5. When the connection processing is completed, the SSAP real address is written and stored to a session connection management table 8, which exists by one-to-one with the connected session, by a session connection SSAP real address memory holding means 6.