PSTN Switch off Jargon Buster

Back in November 2017, BT Openreach announced a Public Switched Telephone Network (PSTN) switch-off plan, aiming to phase out this analogue phone system by December 2025.

The ins and outs of the PSTN switch off can be a bit confusing, so we’ve put together a quick guide to help you get to grips with some of the more complex terminology.

Analogue-to-Digital Conversion

The process of converting analogue signals (traditional voice communication) into digital format, which is essential for newer communication technologies.

BT PSTN Switch-off

The process of discontinuing the Public Switched Telephone Network (PSTN) services provided by British Telecommunications (BT) in favour of newer, more advanced technologies.

Communication Providers (CPs)

Companies that offer communication services to end-users, including traditional telecommunication providers and newer internet service providers offering VoIP or digital telephony.

Copper Decommissioning

The removal or retirement of copper-based infrastructure, such as copper phone lines, as part of the transition to newer technologies.

Customer Premises Equipment (CPE)

The equipment and devices located on the customer's premises, such as telephones, routers, or modems, which may need to be upgraded or replaced during the transition.

Digital Inclusion

Ensuring that all segments of the population have access to and can benefit from digital communication technologies, emphasising equity and accessibility.

Digital Switchover

The transition from analogue to digital technologies. In the context of the PSTN switch-off, it refers to the move from analogue voice transmission to digital alternatives like VoIP.

DSL (Digital Subscriber Line)

A technology that provides internet access by transmitting digital data over traditional copper telephone lines. As PSTN services are switched off, alternatives like fibre-optic broadband or wireless technologies may replace DSL.

Emergency Services Access

Ensuring that emergency services can seamlessly transition to and access the new communication infrastructure during and after the switch-off.

Fallback Options

Contingency plans or alternative communication methods in case of any disruptions or issues during the transition.

Fibre Optic Network

A high-speed data transmission system that uses optical fibres (thin strands of glass or plastic) to transmit data as pulses of light. It forms the basis of modern broadband and telecom infrastructure.


The ability of different systems, networks, or services to work together, facilitating a smooth transition and coexistence of old and new technologies during the migration period.

IP Telephony

A technology that uses the Internet Protocol to transmit voice and multimedia content, often used interchangeably with VoIP.

ISDN (Integrated Services Digital Network)

A set of communication standards for simultaneous digital transmission of voice, video, and other data over the traditional PSTN.


The process of moving customers from the old PSTN infrastructure to the new digital or IP-based network.

NGN (Next-Generation Network)

An advanced telecommunications network that integrates different communication services, including voice, data, and multimedia, over a single IP-based infrastructure.

PSTN (Public Switched Telephone Network)

The traditional telephone network that uses copper wires to transmit analogue voice signals. It is being phased out in favour of digital technologies.

Quality of Service (QoS)

A measure of the overall performance and reliability of a telecommunications service, including factors like call clarity, data speed, and network responsiveness.

Rural Connectivity

Addressing the challenges and ensuring the availability of reliable communication services in rural areas, which may require specific attention during the transition.

Service Level Agreements (SLAs)

Contracts or agreements that define the expected level of service between a service provider (such as a telecom company) and its customers.

Telecoms Regulator

The regulatory body responsible for overseeing and managing telecommunications services. In the UK, this role is fulfilled by Ofcom (Office of Communications).

The British Security Industry Association (BSIA)

A trade association in the United Kingdom, representing companies involved in the professional security sector, including electronic security systems, manned guarding, and related services.


While not directly related to the BT PSTN switch-off, in the context of large projects, "tranche" may refer to phases or stages of the transition, allowing for a gradual and systematic approach.

VoIP (Voice over Internet Protocol)

A technology that enables voice communication and multimedia sessions over the Internet, providing an alternative to traditional PSTN services.

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