SUBSCRIBER MULTIPLE CONNECTION METHOD IN KEY PHONE SYSTEM

摘要

PROBLEM TO BE SOLVED: To attain the originating and incoming of calling while housing many subscribers in one line by providing an ISDN trunk card connecting ISDN. SOLUTION: CPU 110 grasps the state of each port to drive a system, determines and analyze the advance of a speech to control the state of the calling. SCPU 112 shares the function of CPU 110 and always communicating data with a key phone subscriber's circuit 124. A trunk line subscriber's circuit (TRK) 120a to 120c controls the usage of the trunk line of an extension subscriber and a key phone subscriber, and one TRK includes four trunk lines. Extension subscriber's circuit 122a and 122b controls CPU 110 to provide an operation power source for a pertinent subscriber's terminal equipment and connects a speech path part 116 to the pertinent terminal equipment. The key phone subscriber's circuit 124 receives data from a key phone subscriber's terminal to transmit to the speech path part and receives data from the speech path part 116 to transmit to the key phone subscriber's terminal.