Talk:EWSD

Google translation from German. I only transcribed or paraphrased the portions at whose meanings I could guess:

EWSD is a brand name for a Siemens electronic switching system.

Operational area
EWSD can work as local or tandem or combination. There are wire and wireless variants. Customers include Deutche Telekom AG/T-Com, Versatel, COLT Telecom, QSC, Vodafone, Arcor and Romtelecom (Romania). Siemens claims to have sold EWSD in 120 countries.

History
DeTeWe bought its first EWSD under license in 1985 for remote switching. Bosch built its first EWSD as a local exchange in 1986. German Telekom uses EWSD and System 12 (Alcatel), the former more than the latter.
 * DeTeWe didn't buy an EWSD system, but an EWSD licence. In 1985 they sold their first self-built system. --213.39.156.122 (talk) 14:26, 17 December 2007 (UTC)

Construction
Subsystems are packaged in racks of cards, accessible from the front and connected by backplane wiring. Fans at the bottom of the cabinet circulate cooling air.

Hardware
Main subsystems are:

CP (Central Processor) MT (Message Buffer) CCNC (Common Channel Network Control LINE (Analog Line Group) DLU (Digital Line Unit) SN (Switching Network)

All system units are redundant so the inactive side can take over immediately in case of an error.

DLU handles analog and ISDN lines and includes codecs for analog lines, one of the "BORSCHT" functions for subscriber lines. Digital signals are assigned a time slot. DLU concentrates traffic onto a Line B unit, as well as Primary ISDN and V5.2 connections. Supervision and address signaling (dial pulse, DTMF) are also integrated in the DLU. For PCM-30 (E-1) connections to other exchanges, Line C Units are used, which also handle signaling including SS7, MFC R2, IKZ, and E&M.

The Switching Network consists of 4 space division stages of 16x16 switches, and a time division section with 16 stages of 4x4 switches. Control is provided by the CP Co-ordination Processor.

There are the following kinds of Co-ordination Processors:
 * CP103 with max 22,000 call attempts in the busy hour
 * CP112 with max 60,000 call attempts in the busy hour
 * CP113D with max one million call attempts in the busy hour
 * CP113C with max six million call attempts in the busy hour
 * CP113E with max ten million call attempts in the busy hour

Software
The software of EWSD is called APS (Automatic Program System). The APS is on a hard drive and includes the operating system, developed by Siemens in cooperation with Bosch. It is predominantly written in the CHILL language. Application software is switch specific and serves among other things traffic management, path search, and call charging. Support software serves translating programs, binding modules as well as administration of libraries for generating data. Operating and data communication software serve for co-operation of maintenance centers and switching centers.

Technical data

 * Number ofaccess lines to 250,000
 * Number of feeder lines 240,000
 * Traffic connection 25,200
 * Call attempts in busy hour 10 million
 * Operating voltages -48V -60V -90V
 * Rate zones 127, for each zone of 6 tariffs
 * Tariff change-over at 15 minute intervals
 * Space requirement with 10,000 access lines 35 square meters

Jim.henderson 02:17, 27 February 2007 (UTC)

Fair use rationale for Image:EWSD.jpg
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BetacommandBot 18:30, 13 September 2007 (UTC)