The PSTN ‘Switch Off’ is fast-approaching: A brief look at what services are reaching end of life and what alternatives are available. (5-minute read)

You may have heard of the PSTN Switch Off, also referred to as the ISDN Switch Off – it’s no secret but does need to be addressed, and sooner than you may think.

With 2025 fast approaching, it’s time to look at the options for businesses as phone lines are moved into our increasingly digital world. In this article we break down the jargon and acronyms surrounding these services, what the plan is, and what you can do to get ahead. 

What is PSTN?

The Public Switched Telephone Network (PSTN) is a global term for the interconnection of public telephone networks over copper-based materials. They are primarily used for voice calls, fax machines, franking machines, card processing machines and connecting a modem for dial up internet (old technology). It has been in place for decades and uses analogue signalling to allows calls to be made over the copper and fibre telephone lines; it’s also frequently referred to as traditional or fixed line telephony.

As broadband services have increased in reliability and quality over the past 10 years, the PSTN has been evolving to support this change using digital technology. 

What’s the issue?

The legacy infrastructure and equipment serving the PSTN is ageing and becoming increasingly difficult to maintain as it reaches the end of its life. It relies on older technology that doesn’t function well with a modern business and is costly to run, therefore becomes disproportionately expensive for the end-user versus the alternatives.

In 2015, BT announced that they would be phasing out PSTN solutions, with customers no longer being able to purchase these services, and any existing lines completely switched off in 2025. This means the whole PSTN copper network and all associated solutions will no longer be an option and businesses must find an alternative. 

What’s the plan?

The priority for the UK moving forwards is to maintain a high availability fibre-first network. The PSTN currently supports analogue lines, ISDN2 and ISDN30, broadband services such as ADSL (Asymmetric Digital Subscriber Line) and FTTC (Fibre to the Cabinet) as well as EFM (Ethernet First Mile) circuits – all of which will be discontinued over the next couple of years with all support ceasing entirely from 2025.

As these services are made redundant, and phone users must transition into a more digital world, businesses will need to look at alternative solutions… 

When is this happening?

The transition has already begun: many services are no longer available to purchase/upgrade, others are becoming increasingly cost-prohibitive as a deterrent, and exchanges are already being upgraded across the UK.

BT have released a list of exchanges scheduled for upgrade in June and October 2021. Almost 3.5million lines run through these exchanges so this could affect hundreds of thousands of businesses sooner than anticipated. The upgrade is a stop sale on all analogue services and implementation of new circuits to replace the PSTN services. These upgrades will continue until every BT Exchange has transitioned to all-IP service provision before the 2025 deadline.

As so many businesses are looking to get ahead of the PSTN Switch Off, we have created a useful tool on our website where you can check which BT exchange your services run through and when that exchange is scheduled for update.

Check your organisation’s number here.

What are the options?

The ‘Switch Off’ will force users to upgrade to digital VoIP (Voice over Internet Protocol) telephony solutions and address their broadband services in many instances. By doing this, users will benefit from clearer phone calls and phone services that are fit for flexing in the future! Some businesses may have already moved away from PSTN in favour of these services, but others will need to migrate before it’s too late.

There are several options available to businesses but it’s important to select a solution matched to the specific requirements of your organisation and site location. 

SIP Trunking: If you currently own or lease a telephone system, you may elect to use SIP Trunking, which bridges the gap between what you already have and what’s to come; this uses VoIP technology and makes cloud features available while retaining an on-premise telephone system (PBX). With this option, you can preserve the features, numbers and call quality you already receive but add capability and exploit opportunities to future-proof your business.

Hosted: Alternatively, your business could benefit from a fully Hosted solution, meaning there is no physical telephone system in your premises; your calls are transmitted as data over the internet via a highly resilient and secure next-generation network. The telephone system itself is off-site, in a data centre for example, and the features are accessed via subscription user licences. 

There are also options for alternative data services:

Leased Lines: Leased Lines provide high-capacity, dedicated data circuits that are robust, resilient and symmetrical connections with zero contention and scalable speeds. By establishing a direct fibre connection between your premises and your nearest exchange, Leased Lines guarantee flawless connectivity which can scale up or down in line with your changing needs; it not only satisfies your existing requirements but can also manage your future ones.

Fibre to the Premises (FTTP): Ultrafast fibre broadband direct to your site (without any copper lengths) resulting in faster speeds than Fibre to the Cabinet (FTTC) and performance to rival leased line technology for a fraction of the cost. This is not available in all locations, but is expanding all the time. 

Single Order Generic Ethernet Access (SOGEA): SOGEA is your closest alternative to FTTC broadband and is available to order in many exchange areas. It is broadband, but without the requirement for an underlying PSTN line, which means the connection is more reliable with less chance of interference and instability.

Single Order Transitional Access Product (SOTAP): This is a new product to replace ADSL connections. SOTAP delivers a copper path between the end user’s premises and the exchange infrastructure, providing a better experience for customers moving away from end of life WLR (Wholesale Line Rental) products. This is also only deliverable in certain areas at this moment in time but BT anticipate full roll out by September 2021.

Internet of Things (IOT): There are billions of devices worldwide that are connected to the internet to receive and transmit data. IOT SIM cards can be supplied for GSM (Global System for Mobile communications – the internationally used standard platform for mobile phones) units if required for lift/alarm lines and other analogue services. 

Ultimately, you will need to consider your present set-up, determine the features and capabilities you require, review the costs involved and find out which solutions are available in your area – this is where we can really help.

Why Premier Choice?

We have spent the last two decades growing with technological developments in B2B telecommunications. We’re experts in SIP Trunking, Hosted and Data – we’ve been supplying these services since the technology first existed. We see Hosted telephony as an excellent opportunity for many businesses and have developed our Pure Hosted solution to be completely customisable. Our Data services are secure and reliable and we will always work with you to provide you with the right solution for your needs.

As a BT partner, we’ve been preparing for the PSTN ‘Switch Off’ since it was announced and have successfully migrated hundreds of customers, enabling system upgrades and cost efficiencies as well as peace of mind that they will not be affected by the upcoming termination.

You won’t find a blanket response or a one-size-fits-all recommendation when you come to us. For example, if you have recently made an investment in a PBX, you may be inclined towards SIP Trunking to make the most of this outlay. If your system is not compatible to upgrade to SIP, or you require bespoke functionality for each user, you may lean towards a Hosted solution which has minimal upfront costs for hardware and tailorable user packages. Your data provision may well be guided by what’s available to your site but where options are available we will make sure to recommend a service that fully maps to your requirements.

We’re here to work with you to ensure you’re equipped in advance of the planned changes. And as always, all of our solutions are backed up by outstanding Customer Service; including our UK Service Desk, National Field Engineering Team, Account Management, Bespoke Billing Solutions and Customer Support. 

What next?

You’re welcome to use our Exchange Upgrade Number Checker, or feel free to just get in touch with us! Our Business Development Managers are available to audit your current configuration, help you think through your requirements and provide recommendations for moving forward.

To ask for advice, or arrange a no-obligation consultation, please call us today on 020 3701 9229, email with the subject ‘PSTN Switch Off‘ or complete our contact form.

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