Why am I learning Telecommunication Switching Systems

Public switching systems

As part of the digitization of Deutsche Telekom's telephone network, the EWSD (Siemens) and S12 (Alcatel) systems are used for the long-distance and local exchanges.
The serial construction and commissioning of the DIV systems took place from 1984 onwards. With the digitization, the old analog switching technology with the 55 / 55v system with the precious metal motor rotary dials (EMD) and, in some cases, even older mechanical rotary dials was completely replaced.

EWSD - Eelectronic W.ahlsystem D.igital

The EWSD is one of the most widely used public switching systems worldwide. Hardware and software correspond to the international ITU-T and ETSI standards. This system was developed and installed by Siemens and Bosch Telecom.
The most important feature of this system is the central route search through the coupling network and the jointly switched outward and return route of the telephone connection.

Thanks to the flexible system concept, it can be used for a wide variety of applications:
  • Subscriber switching
  • Long distance switching
  • combined mediation
  • International placement
  • Cellular switching
  • Gateways
  • Rural / container brokerage
  • Access network mediation
EWSD supports the following services (Status: 7/98):
  • ISDN (Integrated Services Digital Network)
  • Centrex (virtual PBXs)
  • IN (intelligent networks)
  • Broadband
EWSD supports the following interfaces (Status: 7/98):
  • analog network and subscriber connections
  • ZGS No. 7 for network signaling
  • EDSS1 for ISDN subscriber connections
  • Q3 on the telecommunication management system
  • V5.1 / V5.2 to the access network

S12 - system 12

The most important features of this switching system are the decentralized route search and the outward and return routes of a telephone connection are switched separately.
System 12 (S12) comes from Alcatel (formerly SEL).

Transmission technology

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