PACX (Private Automatic Computer eXchange) was a name given by Gandalf Technologies to their family of data switching products.
The PACX was a centralized switch product that competed with LANs. Desktop modems were connected to a pool of modems at a central location. A data switch at the central location created the required connections between desktop modems and typically a number of main frame computers. The PACX concept was modelled after the needs of a mainframe computer architecture and became obsolete with the development of desktop client–server applications and the development of LANs.
The PACX, with its mainframe utility, was part of an era in which enterprise data services were seen to the province of an Office Controller. The Office Controller was envisaged as a central switch which would interconnect and create all applications and make them available to users. PABX manufacturers of that era (the 1980s) created suites of data applications for the connection of users to mainframe applications. There were even magazine articles touting the victory of the PABX as an Office Controller over its LAN rivals. The PACX was a data PABX without the voice capability
With the development of LANs and cheap PCs with their attendant client/server applications, the Office Controller vision faded away. However the idea is not without merit. It is being re-established in new guises with the development of SIP with Session Border Controllers and Service Oriented Architectures.
The PACX concept is not dead but has been re-adapted to take account of the needs for managed connectivity in a pervasively connected network.