Are 5ESS switches still in use?
Abigail Rogers
Updated on March 01, 2026
The 5ESS Switching System is a Class 5 telephone electronic switching system developed by Western Electric for the American Telephone and Telegraph Company (AT) and the Bell System in the United States. It came into service in 1982, and updated versions are still produced today.
What replaced the 5ESS?
Verizon will begin the replacement of existing Lucent 5ESS switches with Nortel Networks Succession platform. The Nortel Succession network elements that will be deployed include communication servers and associated gateways and peripherals.
What is EWSD system?
The Elektronisches Wählsystem Digital (EWSD), translated to Electronic Digital Switching System in English, is a widely installed German telephone exchange system, originally introduced in 1975 by Siemens AG, but discontinued in 2017.
What is a EWSD switch?
EWSD (Electronic Worldwide Switch Digital, or, in German, Elektronisches WaehlSystem [Digital]) is a widely-installed telephonic switch system developed by Siemens. Digital and analog lines can be combined in the same line groups, allowing full interoperability between digital and analog terminals.
What is ISDN switch off?
What is the ISDN switch off? The copper based PSTN and ISDN network began shutting down in 2020 – with the aim of turning the network off entirely in 2025. A lot of traditional phone systems however use ISDN, although some may use multilines (multiple PSTN lines) which will also be affected by these changes.
How do I access ISDN?
The process of setting up ISDN involves:
- Loading the modem driver disk and programming the modem.
- Pointing the modem toward the right phone numbers.
- Setting your connection speeds for each line.
- Directing your modem to dial your ISP (Internet Service Provider) — this phone number should be provided by your ISP.
Does anyone still use ISDN?
People still use ISDN for internet access in areas where broadband internet isn’t an option. For the most part, ISDN for internet access is being phased out. There have been many attempts to improve the ISDN service. Broadband ISDN, also known as B-ISDN, transmitted data over fiber optic cable.
Why is ISDN being phased out?
Why Are BT Phasing Out ISDN and PSTN? The short answer is that they are old fashioned legacy technologies with associated maintenance costs and drawbacks. PSTN is the traditional telephone line network which carries analogue voice data over copper lines.
What is the 5ESS Switching System?
The 5ESS Switching System is a Class 5 telephone electronic switching system developed by Western Electric for the American Telephone and Telegraph Company (AT) and the Bell System in the United States. It came into service in 1982, and updated versions are still produced today.
Where can I find 5ESS Lucent switch parts?
5ESS Lucent Switch parts can be obtained from Commsource. Contact Commsource for your used, refurbished, surplus, and secondary market Lucent 5ESS Switch plugs, cards, cabinets, bays, power supplies, and more. 5ESS Lucent Switch parts can be obtained from Commsource.
What is a communication module in 5ESS?
Communication Module. The Communications Module (CM) forms the central time switch of the exchange. 5ESS uses a time-space-time (TST) topology in which the Time-Slot-Interchangers (TSI) in the Switching Modules assign each phone call to a time slot for routing through the CM.
Does AT still use 4ESS switches?
As of 2021, AT still operates and maintains approximately 100 #4ESS switches in the public switched telephone network. The Nokia N4E-N1B (New 4ESS) is the ATCA (Advanced Telecommunications Computing Architecture) based next-generation toll switch for AT.
