PURPOSE: To prevent double acquition of a talking circuit by dividing into two talking circuits provided between exchanges, and by giving both exchanges the right to select groups of halved talking circuits.

CONSTITUTION: Talking circuits, provided between exchanges EXa and EXb as many as (n), are halved into groups of circuits TLa and TLb. The right to select circuit groups TLa and TLb is given to exchanges EXa and EXb, and memory units Ma and Mb are stored with circuit information of groups TLa and TLb. When a call arrives at exchange EXa, a free circuit of circuit group TLa is selected by the circuit control information of unit Ma and selective signal IAM with an added label of the circuit number is sent to exchange EXb by way of private data link CSC. To acquire a talking circuit without the right to select, temporary label is appended to signal IAM, which is sent to exchange EXB via link CSC. By making use of information in unit Mb, exchange EXb selects a free circuit of TLb and sends the selected circuit number to exchange EXa via link CSC by adding to the temporary label, so that information transmission and reception will come into effect via this circuit.