PX (private exchange)
An internal telephone exchange serving a single organization and having no connection with a public exchange. Also private automatic exchange (PAX). Other types of private exchange include:
- Private automatic branch exchange (PABX): A private automatic telephone exchange that provides for the transmission of calls internally and to and from the public telephone network. Also private branch exchange (PBX).
- Private automatic telex exchange (PATX): Provides telex service within and without an enterprise (largely obsolete).
- Private manual branch exchange (PMBX): Private, manually operated telephone exchange that provides private telephone service to an organization and allows calls to be transmitted to or from the public telephone network.
- Private digital exchange (PDX): Private exchange employing digital transmission techniques.
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