Abstract: A network linkage type private branch exchange system including a plurality of private branch exchanges, a plurality of telephone network interfaces for relaying data between a plurality of telephone networks and each private branch exchange, a plurality of terminal devices such as an extension for transmitting the data between the respective private branch exchanges and a plurality of operators, a plurality of computers each connected to each private branch exchange for conducting predetermined processing based on the data, and a data communication line to which each private branch exchange is connected, in which each private branch exchange transmits data to a computer connected to an arbitrary private branch exchange other than the private branch exchange in question through the data communication line.

Abstract: A private branch exchange system facilitates the expansion of extension telephones and extension groups, and can quickly transfer an overflow call from extension telephones supported by one private branch exchange (“PBX”) to an extension telephone supported by another PBX. The PBX system is formed such that a plurality of PBXs connected to telephone network and connecting a plurality of extension telephones are composed a PBX with communication line. Each PBX queues an incoming call arriving through telephone network in reception sequence queue common to the overall PBX network. Each PBX scans the distribution sequence queue common to the overall PBX network to select an optimal extension telephone.

Abstract: A network linkage type private branch exchange system including a plurality of private branch exchanges, a plurality of telephone network interfaces for relaying data between a plurality of telephone networks and each private branch exchange, a plurality of terminal devices such as an extension for transmitting the data between the respective private branch exchanges and a plurality of operators, a plurality of computers each connected to each private branch exchange for conducting predetermined processing based on the data, and a data communication line to which each private branch exchange is connected, in which each private branch exchange transmits data to a computer connected to an arbitrary private branch exchange other than the private branch exchange in question through the data communication line.