PURPOSE: To call plural extensions at once by simultaneously reading plural opponent destinations from the single extension and executing a call with the opponent destination which makes a response at first.

CONSTITUTION: At fist, when call origination is executed from an extension 5, dialing is executed as follows; (a special number for plural opponent destinations calling)+(the number of an extension 6)+(a special number to show the partition of a calling destination number)+(the number of an extension 7), (a special number to show the partition of a calling destination number)+(the number of an extension 8). A central control device 2 receives this dialing by a dial receiving device 4 and it is stored in a storage 3 that the extension 5 is in the condition of plural opponent destinations calling operation and the calling destinations are the extensions 6-8. When any one of the extensions 6-8 is in an idle condition, the idle extension is called. When the extension 6 makes the response at first, the central control device 2 forms a channel between the extensions 5 and 6 by a channel switch 1 and stops the calling to the extensions 7 and 8.