Method of recovering speech path of pre-engaged call on restarting keyphone exchange system

摘要

A method of recovering a speech path of a pre-engaged call upon restarting a keyphone exchange system due to the occurrence of a system failure. The method includes the steps of initializing all hardware and all software except for a subscriber's table buffer of said keyphone exchange system when being generated a predetermined restarting signal of said system; initializing a variable number of ports in the communication control software as a given initial value; generating an address of a port number corresponding to said variable number of ports in said subscriber's table buffer; checking whether a talk bit of a line status word in a port corresponding to said port number is set or not, said line status word indicating the state of said port; obtaining a subscriber's port number from a line number buffer and an opposite subscriber's port number from an opposite party if said talk bit is set, said line number buffer storing said subscriber's port number and said opposite party storing said opposite subscriber's port number; and forming said speech path of said call by connecting said subscriber's port number in said line number with said opposite subscriber' s port number in said opposite party.