EWSD
Encyclopedia
EWSD is one of the most widely installed telephone exchange
systems in the world. EWSD can work as a local or tandem switch or combined local/tandem, and for landline
or mobile phones. It is manufactured by Siemens AG
, who claims that EWSD switches perform switching for over 160 million subscriber lines in more than 100 countries.
DeTeWe bought its first EWSD under license in 1985 for remote switching. Bosch
built its first EWSD as a local exchange in 1986. Deutsche Telekom
, formerly Deutsche Bundespost, the largest German telephone company, uses EWSD and System 12 (Alcatel), the former more than the latter.
In 2007, Nokia
Corporation and Siemens AG formed the new company Nokia Siemens Networks
, and responsibility of further development and shipments of the EWSD system is dependent on this new company.
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 signalling
, IKZ (dial pulse), 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:
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.
Telephone exchange
In the field of telecommunications, a telephone exchange or telephone switch is a system of electronic components that connects telephone calls...
systems in the world. EWSD can work as a local or tandem switch or combined local/tandem, and for landline
Landline
A landline was originally an overland telegraph wire, as opposed to an undersea cable. Currently, landline refers to a telephone line which travels through a solid medium, either metal wire or optical fibre, as distinguished from a mobile cellular line, where transmission is via radio waves...
or mobile phones. It is manufactured by Siemens AG
Siemens AG
Siemens AG is a German multinational conglomerate company headquartered in Munich, Germany. It is the largest Europe-based electronics and electrical engineering company....
, who claims that EWSD switches perform switching for over 160 million subscriber lines in more than 100 countries.
DeTeWe bought its first EWSD under license in 1985 for remote switching. Bosch
Robert Bosch GmbH
Robert Bosch GmbH is a multinational engineering and electronics company headquartered in Gerlingen, near Stuttgart, Germany. It is the world's largest supplier of automotive components...
built its first EWSD as a local exchange in 1986. Deutsche Telekom
Deutsche Telekom
Deutsche Telekom AG is a telecommunications company headquartered in Bonn, Germany. It is the largest telecommunications company in Europe....
, formerly Deutsche Bundespost, the largest German telephone company, uses EWSD and System 12 (Alcatel), the former more than the latter.
In 2007, Nokia
Nokia
Nokia Corporation is a Finnish multinational communications corporation that is headquartered in Keilaniemi, Espoo, a city neighbouring Finland's capital Helsinki...
Corporation and Siemens AG formed the new company Nokia Siemens Networks
Nokia Siemens Networks
Nokia Siemens Networks is a global data networking and telecommunications equipment company headquartered in Espoo, Finland. It is a joint venture between Nokia of Finland and Siemens of Germany...
, and responsibility of further development and shipments of the EWSD system is dependent on this new company.
Hardware
Main subsystems are:- CP (Central Processor)
- MB (Message Buffer)
- CCNC (Common Channel Network Control)
- LINE (Analog Line Group)
- LTG (Line Trunk Group)
- DLU (Digital Line Unit)
- SN (Switching Network)
- PA (ISDN Primary Access)
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
BORSCHT
BORSCHT is an acronym for:Battery supply to subscriber lineOvervoltage protectionRinging current supplySupervision of subscriber terminalCoder and decoderHybrid, 2 wire to 4 wire conversionTesting...
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
SS7
SS-7 can stand for:* Signaling System #7, a set of telephone signaling protocols.* The R-16 missile, with NATO reporting name SS-7 Saddler.* China Railways SS7, an electric locomotive model in China.* Super Socket 7, a chip socket introduced by AMD...
, MFC R2 signalling
R2 signalling
R2 is a 1950s- and 1970s-era channel-associated-signalling signalling protocol used outside of the former Bell System to convey information along a telephone trunk between two telephone switches in order to establish a single telephone call along that trunk....
, IKZ (dial pulse), 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 CHILLCHILL
In computing, CHILL is a procedural programming language designed for use in telecommunication switches . The language is still used for legacy systems in some telecommunication companies and for signal box programming.The CHILL language is similar in size and complexity to the Ada language...
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
Communication software
Communication software is used to provide remote access to systems and exchange files and messages in text, audio and/or video formats between different computers or user IDs...
serve for co-operation of maintenance centers and switching centers.
Technical data
- Number of access 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