PSTN and ISDN Switch-Off Guide 2027

Get Switched On about the Switch Off#

Welcome to our PSTN and ISDN Switch-Off Hub – your central resource for the latest information about the changes ahead – as BT Openreach prepares to retire the Public Switched Telephone Network (PSTN) and Integrated Services Digital Network (ISDN) in 2027.

TalkTalk Business is fully committed to supporting our customers through this journey. Due to our extensive network investments, we’re able to offer more options than other providers, helping your business stay connected and embrace the new digital future with our range of alternative solutions.

On this page you'll find key dates to take note of, simple explanations about the switch-off and what it means for your business, as well as some frequently asked questions to prepare you for the changes ahead.

Not ready for a post-PSTN & ISDN world? Don’t worry, we have options to keep your business connected and maintaining operational continuity through this transitional period.

We'll be regularly updating this page with helpful information, so be sure to check back.

BT Openreach are raising prices#

As the PSTN and ISDN switch-off in January 2027 approaches, BT Openreach is increasing its wholesale WLR prices to communications providers to encourage customers to transition to alternative services.

BT Openreach are incrementally raising prices of WLR PSTN and ISDN lines to all communications providers this year in three steps. As such, by October 2026, line rental prices will double.

Unfortunately, these cost increases from BT Openreach mean that all communication providers (TalkTalk Business included) have no choice but to mirror the changes to WLR PSTN and ISDN line prices. The sooner your business makes the switch to an alternative solution, the less you’ll have to pay.

TalkTalk Business has the right options for you#

At TalkTalk Business, our range of full fibre or part-fibre broadband with digital voice solutions and Metallic Path Facility (MPF) services offer better value, speeds and reliability. They will ensure that you won’t be without broadband or phone services when the switch-off happens.

Used by thousands of businesses, our Metallic Path Facility (MPF) lines will continue to support your existing voice service – so you don’t need to migrate to a digital voice service – whilst our broad portfolio of digital voice and cloud-based solutions offer improved ways of working for your teams and enhanced service for your customers.

Speak to us today to set your communications up for the future#

The sooner you get in touch with us, the more options you’ll have. Save money, reduce disruption and transition to a future-proof solution by reaching out to our team today on 0800 083 3003 to discuss your options. Alternatively, if you have an Account Manager, you can contact them via the usual channels.

What is the PSTN and ISDN switch-off?#

The PSTN allows users to make and receive traditional phone calls and is comprised of BT Telephone exchanges run by Openreach. Installed in the 1980s, it's now very outdated.

Integrated Services Digital Network (ISDN) is an older type of digital communication voice and data service and runs over the PSTN. It is also being switched off by January 2027.

What services are affected? #

The BT PSTN switch-off is achieved through the withdrawal of Wholesale Line Rental (WLR) lines (which connect to the PSTN). The following Openreach “All-IP” lines replace WLR:

• SOGEA – Single Order Generic Ethernet Access (Fibre to the Cabinet broadband without the WLR phone line)

• SOGFast – the G.Fast variant of SOGEA (not widely deployed)

• FTTP – Fibre to the Premise broadband

These BT Openreach lines do not connect to the PSTN and require communications providers to offer VoIP telephony services. WLR lines went into stop-sell in 2023, with all customers to be migrated off by January 2027 at the latest.

What are your options?#

It's important to note that Openreach has not changed the status of Metallic Path Facility (MPF) lines that TalkTalk Business use, and these lines remain fully available, unaffected by the PSTN switch-off.

So if your business isn’t ready to transition to a digital voice service, we’ve got you covered. In addition to digital voice solutions, TalkTalk Business also continues to provide telephony and broadband services over Metallic Path Facility (MPF), allowing customers use of their existing phones beyond January 2027. More details on this below.

Digital voice#

TalkTalk Business offers a range of Voice over IP (VoIP) telephony services to replace traditional PSTN and ISDN connections.

Digital Phone Line is for single users and works over the broadband connection. Your existing phones must plug into your router or broadband hub (or via an adapter). It comes out of the box with all the main calling features a business needs. TalkTalk Business offers Digital Phone Line over Business Fibre (SoGEA), or Business Full Fibre (FTTP). For PSTN multi-line/ISDN2 or ISDN30 customers, we offer Zoom products for a fully hosted telephony and UC solution.

MPF#

If you’re not ready to move to a digital voice service, you can still prepare for the 2027 switch-off with Metallic Path Facility (MPF) phone lines. MPF phone lines connect from our equipment in the BT exchanges to customers’ premises.

TalkTalk Business's MPF phone lines are unaffected by WLR stop-sell or withdrawal in 2025, which means that we can continue to offer broadband and Fibre to the Cabinet (FTTC) options with MPF. MPF FTTC is functionally identical to SOGEA in respect of broadband performance and availability.

MPF phone lines can give you more time to plan and implement your digital strategy before switching to a digital voice service when you’re ready. Find out more about our MPF offering here.

Is MPF widely available?#

TalkTalk Business currently have equipment in 3000+ Openreach exchanges across the UK, which equates to 92% national coverage where customers can (or are) using MPF phone lines.

When it comes to digital voice, in addition to Digital Phone Line, TalkTalk Business also offers other IP based telephony options including Zoom, SIP (Session Initiation Protocol) and Mitel Digital Phone Line solutions.

We're working hard to ensure that all our customers have alternative communication solutions available and will continue to share updates as our coverage increases further.

PSTN & ISDN Switch Off FAQs #

• What is the PSTN and why is it being switched off? The Public Switched Telephony Network (PSTN) is the communications infrastructure that enables voice communication through conventional landline phones in the UK. It's comprised of BT Telephone exchanges. Although the current PSTN was installed in the 1980s, the network was first set up over 100 years ago and is now very outdated.

• What happens when the BT Openreach PSTN is switched off? When the BT Openreach PSTN is switched off, all WLR line connections will stop working. Now is the time to ensure you have a digital voice or MPF solution in place ahead of the switch-off on 31^st January 2027.

• When is this going to happen? It's happening now. BT Openreach announced the retirement of the PSTN in 2017. In September 2023, WLR lines went into “stop-sell” stage, ahead of a full planned switch-off by January 2027.

• What digital voice options do TalkTalk Business offer? TalkTalk Business offers a range of digital voice solutions, from single line Digital Phone Line to Zoom and Mitel solutions for up to hundreds of users. We also offer SIP Trunking.

• What is Digital Phone Line? TalkTalk Business Digital Phone Line calls use Voice over Internet Protocol (VoIP). Digital Phone Line works over the broadband connection. Customers can plug their existing phones into the router or broadband hub. It's a great, cost-effective option with advanced features to better handle calls.

• Is PSTN the same as landline? No. Your landline connects to the PSTN. PSTN refers to the BT Openreach telephone exchange network, which the majority of UK premises connect landlines to.

• Will I lose my landline in 2027? If you don't make the switch to a digital voice or MPF solution by 2027, your landline will cease to function. Ultimately, all WLR lines will no longer work after 31st January 2027. To avoid operational disruption, speak to us about your options as soon as you can.

• What is ISDN and why is it being switched off? ISDN is a business version of PSTN. It was commonly used to connect to Private Branch Exchanges (PBXs) and it's being switched off at the same time as PSTN.

• What has replaced ISDN? ISDN is being superseded by IP-based voice technology. SIP Trunking is a strong ‘like for like’ replacement for ISDN. It connects your phone system to our network using an IP connection – such as Business Fibre or Full Fibre – so that you can run voice calls over the internet. You can explore our SIP Trunking services here. To find out more about our business fibre broadband solutions, click here.

• What does the switch- off mean for the BT telephony service? BT only provides WLR Openreach lines. It therefore could only provide digital voice over new Openreach “all-IP” lines from September 2023.

• Which access services and technologies will TalkTalk Business offer in the future? We will continue to offer MPF phone lines within our network footprint, including broadband. This helps customers who aren't ready for a digital voice solution.