PURPOSE: To equalize the load among the server terminals by selecting the server terminal having the least number of client terminals in charge as its own server terminal among those server terminals that received the server terminal answer messages from the client terminals requesting the server terminals.

CONSTITUTION: When a client terminal 1-1 kept in an answer waiting state receives the server terminal answer messages from the server terminals 2-1 and 2-2, a CPU 14 analyzes the information on MES TYP (message type) and decides that the terminal 2-1 has the least number of connected client terminals at present. Then the CPU 14 produces the format information and sends this to a circuit 3. Then a CPU 24 of the terminal 2-1 analyzes the received information, and DST ADR (transmitting destination address) recognizes the connection secured even to the terminal 1-1 based on the information on the MES TYP serving as the address of its own terminal and updates the client terminal charging number 01H (server terminal request message) of a RAM 23 to 02H (server terminal answer message). Thus the load is equalized between both terminals 2-1 and 2-2.