PSTN Switch Off 2027: Openreach Shutdown Guide

The PSTN switch off is the permanent retirement of the UK's copper telephone network, scheduled for 31 January 2027. It ends traditional analogue landlines and ISDN services, replacing them with internet-based voice (VoIP). Every business that still relies on a BT phone line, ISDN circuit, or any device connected to the copper network needs to migrate before that date or risk losing service entirely. The good news is that modern alternatives are more capable and often cheaper than what they replace. Platforms like PBX.IM, which provides hosted cloud PBX with UK virtual phone numbers, make the landline to VoIP transition straightforward for businesses of all sizes.

TL;DR

• The UK's copper telephone network shuts down permanently on 31 January 2027, affecting landlines, ISDN, fax, alarms, lifts, and payment terminals.
• Businesses need to audit every line, map dependencies, and migrate to VoIP, SIP trunking, or a hosted UCaaS platform before the deadline.
• Starting early avoids porting delays, hardware shortages, and last-minute price spikes that are already affecting businesses leaving it too late.

What is the PSTN switch off? (Openreach's PSTN shutdown explained)

PSTN stands for Public Switched Telephone Network: the analogue copper-wire infrastructure that has carried voice calls across the UK since the 1800s.

Openreach is retiring it because the network is old, expensive to maintain, and physically incapable of carrying the bandwidth that modern digital services require. Keeping it running alongside newer fibre infrastructure makes no economic or operational sense, and BT has been open about the fact that it simply cannot support two parallel networks indefinitely.

It is worth being clear on the distinction between PSTN and ISDN. PSTN carries analogue voice. ISDN (Integrated Services Digital Network) runs digital channels over the same copper pairs and has long been the standard for multi-line business phone systems. Both technologies depend on the same physical copper infrastructure, which is why both are being retired at the same time on the same date.

Openreach owns the wholesale infrastructure. BT, along with around 600 other communications providers, sells services on top of it. That means the switch off affects customers across virtually every UK phone provider, not just those on BT directly.

When is the PSTN switch off? Key dates and timeline

Has the deadline moved?

Yes. The original Openreach PSTN shutdown date was December 2025. Ofcom and industry groups pushed for an extension after concerns about vulnerable users, particularly those relying on telecare devices and personal alarms that run over analogue lines. The deadline was moved to 31 January 2027 to give providers more time for safe, managed migrations.

No further extension is expected. Ofcom has been clear that this is the final date, and Openreach has been preparing the network accordingly. Businesses that treat the extended deadline as breathing room rather than an action window are taking a significant risk.

Who and what is affected by the Openreach PSTN shutdown 2027?

Any device or service that depends on a copper telephone line is affected. This includes more than most businesses realise on first assessment.

• Traditional analogue landlines (single-line and multi-line business lines)
• ISDN2e and ISDN30 phone systems (the backbone of most multi-site business telephony)
• Fax machines connected to a BT line
• Lift emergency phones (regulated under EN 81-28; non-compliance carries regulatory and insurance consequences)
• Alarm signalling units and monitored intruder alarms (many use a dedicated PSTN line to report to a monitoring centre)
• Door entry and access control intercoms wired into a phone line
• PDQ payment terminals that dial out over a landline
• CCTV and DVR systems that use a phone line for remote access
• Telecare and personal alarm devices for lone workers or vulnerable individuals
• Modems, EPOS systems, and franking machines that communicate over copper

If a device has a phone socket, it needs assessing before 31 January 2027, when landlines will be phased out

What replaces PSTN? VoIP, SIP and hosted phone systems

The three main replacement technologies cover different business needs and starting points.

VoIP and hosted PBX deliver voice calls entirely over a broadband connection, using desk phones, softphone apps on laptops, or mobile apps. There is no on-site phone hardware beyond the handsets themselves. This is the right fit for most small and medium-sized businesses, particularly those that rent rather than own their phone system.

SIP trunking keeps an existing on-premises PBX in place but replaces the ISDN circuits that feed it with SIP channels over broadband. This is the sensible option for organisations that have recently invested in a capable on-site PBX and want to preserve that capital investment while still meeting the 2027 deadline.

UCaaS (Unified Communications as a Service) combines voice, video, instant messaging, and meetings in a single cloud platform. It goes further than a like-for-like line replacement and suits organisations that want to modernise collaboration more broadly alongside the network migration.

PBX.IM sits across all three of these categories, offering hosted cloud PBX, UK SIP trunking, Microsoft Teams Direct Routing, and local UK virtual phone numbers, all from a single platform with transparent pricing.

The landline to VoIP transition: Digital Phone Switch Over guide

Moving from PSTN to VoIP is not technically complicated, but it does require planning. The businesses that run into problems are almost always those that underestimate the number of lines they have, discover a dependency too late, or leave number porting until the final weeks.

Your main replacement options

• Like-for-like landline replacement. A single-line business ports its number, connects an ATA adapter to the router, and continues using existing handsets. The cheapest and simplest path.
• Hosted PBX / cloud phone system. Recommended for most businesses with 5 to 250 users. No server hardware on site; handsets or softphones connect over the internet. Features like call routing, voicemail to email, and auto-attendant are included.
• SIP trunks into an existing PBX. Preserves the on-site investment if the PBX is recent and SIP-capable. The ISDN circuits are replaced with SIP channels; everything else stays the same.
• Full UCaaS platform. Voice, video, chat, and contact centre in one place. Suited to organisations modernising more than just telephony.

Step-by-step migration checklist

1. Audit every line on every site. Do not rely on the BT bill alone. Walk the building physically. Note the line type (PSTN or ISDN), what is plugged into it, and what depends on it. Watch out: businesses regularly find fax lines, alarm lines, and lift lines that no one in the IT team knew existed.
2. Map all dependencies. Lift emergency phones, alarm signalling units, payment terminals, door entry systems, and any device with a phone socket. Each one needs a plan. Watch out: lift lines and telecare devices have regulatory compliance implications beyond just continuity of service.
3. Check your connectivity. What broadband do you have at each site? Is FTTP available? Is your upload speed and contention ratio sufficient to carry concurrent voice calls without quality issues? A good rule of thumb is 100 kbps per concurrent call, but a proper assessment from your provider is worth doing.
4. Choose your replacement architecture. Hosted VoIP, SIP trunks, or UCaaS: the right answer depends on your existing equipment, your headcount, whether you run a contact centre, and how much you want to simplify the overall setup. Watch out: hosted PBX is right for most SMBs, but if you have a recent on-site PBX, replacing it before it is amortised is unnecessary.
5. Plan number porting early. Porting a number from one provider to another typically takes 10 to 15 working days. As January 2027 approaches, porting queues will lengthen significantly. Watch out: any error in the porting request (mismatched account details, incorrect address) restarts the process from scratch.
6. Pilot with one team or site first. Test call quality, headset compatibility, and call routing on a small group before rolling out to the whole business. Watch out: issues discovered during a pilot cost very little to fix; the same issues discovered on go-live day are far more disruptive.
7. Decommission old lines properly. Once you have migrated, cancel the old PSTN or ISDN lines formally. Openreach billing tails, where charges continue on ceased services, are a well-documented problem and a cost that catches businesses off guard.
8. Document the new estate. Keep a register of all numbers, users, devices, and emergency service information including CLI presentation and physical location data for emergency calls. Watch out: emergency location data is a regulatory requirement; make sure your VoIP provider supports it.

What it costs and how to budget a digital phone switch over

VoIP pricing varies depending on whether you go for a per-user hosted system or a SIP trunk arrangement.

Typical market ranges for UK businesses:

• Hosted VoIP per user: between £8 and £25 per user per month, depending on the feature set and number of included minutes
• SIP channels: roughly £5 to £15 per channel per month, with call costs on top
• Setup and porting fees: often between £50 and £200 per site, depending on complexity

PBX.IM pricing is positioned to undercut most enterprise-tier providers while matching them on features. The platform offers flexible monthly plans with no long-term contracts, transparent per-channel pricing for SIP trunks, and free inbound UK virtual phone numbers on most plans. For a business migrating 10 users, the monthly cost with PBX.IM typically comes in well below the mid-range market rate.

Risks of ignoring the Openreach PSTN shutdown

Leaving migration until after 31 January 2027 is not a grey area. The consequences are concrete.

• Complete loss of voice service from the PSTN shutdown date, with no fallback on the copper network.
• Lift-line non-compliance under EN 81-28, which creates regulatory exposure and may void building insurance.
• Alarm signalling failure, which typically voids monitored alarm insurance policies.
• Payment terminals stop working, with direct and immediate revenue impact for any business processing card payments over a phone line.
• Last-minute migration problems: hardware availability tightens, number porting queues lengthen, engineer slots become scarce, and supplier pricing rises as demand spikes.

The businesses most exposed are those with complex estates: multiple sites, legacy alarm systems, lift lines, and ageing ISDN PBXs. These take longer to migrate than a simple broadband phone swap, and that time is running out.

How PBX.IM makes the PSTN switch off painless for UK businesses

PBX.IM is built specifically for businesses making exactly this move. The platform handles the full range of migration scenarios without requiring multiple providers or complex integration work.

Number porting is handled directly, with a clean process and support throughout to avoid the delays that come from porting errors.

UK virtual phone numbers are available across hundreds of area codes, so businesses can maintain local presence or set up new numbers without any physical line infrastructure.

UK SIP trunking gives businesses with an existing SIP-capable PBX a straightforward path to replace ISDN circuits, keeping the existing hardware in place.

Microsoft Teams Direct Routing connects Teams to the PSTN (or rather, to VoIP) so businesses running Teams for internal collaboration can also use it for external calls, without needing a separate phone system.

Pricing is flexible and monthly, with no long-term contract lock-in. Setup is fast enough that a small business can be live the same day, and the platform scales from a single number to enterprise deployments.