External PBX system and external PBX device

Abstract

An external voice switchboard system includes a dedicated exchange and an external voice switchboard device. The external voice switchboard device includes a first connection port, a second connection port, a data storage device, and a first processing device. The first connection port is connected to a public switched telephone network (PSTN). The second connection port is connected to a second telephone connection port of the dedicated exchange. The first processing device is electrically connected to the first connection port, the second connection port, and the data storage device. The first processing device transmits a dialing signal corresponding to an extension number to the dedicated exchange through the second connection port. The dedicated exchange transmits the dialing signal to the telephone of the corresponding extension number. When the first processing device determines that the telephone of the corresponding extension number responds to the dialing signal, the first processing device transfers the first call connection to the telephone of the corresponding extension number.

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