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The Strowger switch is the first commercially successful electromechanical stepping switch telephone exchange system. It was developed by the Strowger Automatic Telephone Exchange Company founded in 1891 by Almon Brown Strowger. Because of its operational characteristics, it is also known as a step-by-step (SXS) switch.
EMS-1 (The ITEC Electronic Modular Switch is an electronic direct control switching system. The modules are combined to form a complete switch or any of the modules can be added to your present Step-by-Step Systems.) EMS-2 (The EMS-2 RURAL SWITCH is a stored program control analog switch designed to be cost-effective in small exchanges.
In data communications, an automatic switching system is a switching system in which all the operations required to execute the three phases of Information transfer transactions are automatically executed in response to signals from a user end-instrument. [1]
The GTD-5 EAX (General Telephone Digital Number 5 Electronic Automatic Exchange) is the Class 5 telephone switch developed by GTE Automatic Electric Laboratories. This digital central office telephone circuit switching system is used in the former GTE service areas and by many smaller telecommunications service providers .
Automation replaced human operators with electromechanical systems, and telephones were equipped with a dial by which a caller transmitted the destination telephone number to the automatic switching system. A telephone exchange automatically senses an off-hook condition of the telephone when the user removes the handset from the switchhook or ...
In 1922, common control was introduced in Strowger-type step-by-step systems, [2] resulting in the first installations of Director systems in Havanna, Cuba in 1924, and in London, England in 1927. By the mid-1920s, common control ideas had extended to include marker systems for testing for idle trunks .
With the advances of digital electronics starting in the 1960s telephone switches employed semiconductor device components in increasing measure. In the late 20th century most telephone exchanges without TDM processing were eliminated and the term electronic switching system became largely a historical distinction for the older SPC systems.
It commenced service in Seneca, Illinois on March 25, 1982, and was destined to replace the Number One Electronic Switching System (1ESS and 1AESS) and other electromechanical systems in the 1980s and 1990s. The 5ESS was also used as a Class-4 telephone switch or as a hybrid Class 4/Class 5 switch in markets too small for the 4ESS.