In 1969 IBM

IBM

International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 started marketing in five European countries the IBM 2750 Switching System – worldwide, the first stored-program-controlled PABX (Private Automatic Branch Exchange). Previously only electromechanical Strowger

Strowger switch

The Strowger switch, also known as Step-by-Step or SXS, is an early electromechanical telephone switching system invented by Almon Brown Strowger...

 and Crossbar

Crossbar switch

In electronics, a crossbar switch is a switch connecting multiple inputs to multiple outputs in a matrix manner....

 PABXs were available.

The 2750 was sold in France

France

The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, Germany

Germany

Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

, Italy

Italy

Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...

, and Belgium

Belgium

Belgium , officially the Kingdom of Belgium, is a federal state in Western Europe. It is a founding member of the European Union and hosts the EU's headquarters, and those of several other major international organisations such as NATO.Belgium is also a member of, or affiliated to, many...

. The other systems were sold in these countries and the United Kingdom

United Kingdom

The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...

. The Netherlands

Netherlands

The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...

 installed some in IBM sites.

The family of IBM 1750, 2750 and 3750 Switching Systems was developed from the IBM 1800

IBM 1800

The IBM 1800 Data Acquisition and Control System was a process control variant of the IBM 1130 with two extra instructions , extra I/O capabilities, 'selector channel like' cycle-stealing capability and three hardware index registers....

 by the IBM La Gaude Research Laboratory near Nice

Nice

Nice is the fifth most populous city in France, after Paris, Marseille, Lyon and Toulouse, with a population of 348,721 within its administrative limits on a land area of . The urban area of Nice extends beyond the administrative city limits with a population of more than 955,000 on an area of...

, France for European markets only. Each system included twin stored-program controller

Stored Program Control exchange

Stored Program Control exchange is the technical name used for telephone exchanges controlled by a computer program stored in the memory of the system. Early exchanges such as Strowger, panel, rotary, and crossbar switches were electromechanical and had no software control...

s (each with some 600,000 lines of code, and nightly automatic switchover), twin disks, and solid-state

Solid state (electronics)

Solid-state electronics are those circuits or devices built entirely from solid materials and in which the electrons, or other charge carriers, are confined entirely within the solid material...

 switching. Extension

Extension (telephone)

An extension telephone is an additional telephone wired to the same telephone line as another. In middle 20th century telephone jargon, the first telephone on a line was a "Main Station" and subsequent ones "Extensions". Such extension phones allow making or receiving calls in different rooms,...

, trunk and tie line

Tie line

A tie line, also known as a tie trunk, is a communication connection between extensions of a private telephone system, typically two PBXes.-References:...

s were connected by discrete transistor

Transistor

A transistor is a semiconductor device used to amplify and switch electronic signals and power. It is composed of a semiconductor material with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current...

s 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.

Extension facilities

Facilities for the extensions were revolutionary at the time and particularly valued by organisations in financial and other industries with relatively highly paid office-based employees:

• Touch-tone telephones (then practically new to Europe)
• Call rerouting from multiple extensions to answer points
• Camp on to a busy extension or external circuit with automatic call back
• Short-code dialling to national and international numbers
• Temporary call barring
• Distinctive ring cadences
• Dialled paging
• Group answering
• Authorised user intrusion
• Add-on third party
  Conference call
  A conference call is a telephone call in which the calling party wishes to have more than one called party listen in to the audio portion of the call. The conference calls may be designed to allow the called party to participate during the call, or the call may be set up so that the called party...
  
  
• Call pick-up
  Call pick-up
  Call pick-up is a feature used in a telephone system that allows one to answer someone else’s telephone call. The “call pick-up” feature is accessed by pressing a preprogrammed button , or by pressing a special sequence of buttons on the telephone set.In places where “call pick-up” is used, the...
  
  
• Non-dialled connection

Management facilities

Most management facilities were new to the PABX market:

• Extension number and facility changes made from a central keyboard
• Call cost recording
• Classes of service for extensions
• Traffic analysis
• Night service
  Night service
  In general, a night service is any service that operates at night, such as a night-time public transport service or a 24-hour telephone support service....
  
  

Data facilities

The then-novel data facilities included:

• Data collection available from every touch-tone extension to the switching system or through it to an IBM computer
• “Touch-tone” access-control
  Access control
  Access control refers to exerting control over who can interact with a resource. Often but not always, this involves an authority, who does the controlling. The resource can be a given building, group of buildings, or computer-based information system...
  
   and attendance recording
  Time and attendance
  Time and attendance, or Workforce Management, systems are used by companies of all sizes to record working hours of employees primarily in order to pay their wages. Some companies have a requirement to record the number of hours spent on specific tasks in order to cost jobs accurately...
  
   terminals connected to normal extension lines
• Contact monitoring and operation

IBM’s customers for instance used the data functions for staff to report chargeable activity from their telephones.

Later additional facilities

Over time IBM introduced further functions:

• Satellite operation (remote operator call handling)
• The IBM Audio Distribution System (the then-novel centralised message recording for 1000 users)
• Partitioning: multiple organisations using one system

The systems needed considerable space, air conditioning and secure electricity night and day (from about 2 to 15 kilowatts ).

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