In 1969 IBM started marketing in five European countries the IBM 2750 Switching System – worldwide, the first stored-program-controlled PABX (Private Automatic Branch Exchange). Previously onlyelectromechanical Strowger and Crossbar PABXs were available.
The family of IBM 1750, 2750 and 3750 Switching Systems was developed from the IBM 1800 by the IBM La Gaude Research Laboratory near Nice, France for European markets only. Each system included twin stored-program controllers (each with some 600,000 lines of code, and nightly automatic switchover), twin disks, and solid-state switching. Extension, trunk and tie lines were connected by discrete transistors on plug-in panels.
|System||Year first marketed||Extensions||Trunks + tie lines||Operator desks|
|IBM 2750 Switching System||1968||100-500?|
|IBM 3750 Switching System||1970||250-2200?||300 Max?|
|IBM 1750 Switching System||1979||100 - 760||0 - 96||1 - 5|
The systems all had both voice and data functions – the marketplace largely bought them for their then-new voice and management functions. Early-1960s computers had hardly any typewriter-like terminals and no screens – the IBM Switching Systems introduced the novelty of simple data capture from touch-tone telephones.