Imagine the reservation line goes dead mid-shift, the card machine starts throwing errors, and the background music system drops out because it relied on an ageing broadband connection nobody had thought about in years. For a restaurant, that is not a minor inconvenience. It is lost covers, frustrated guests, and a queue at the door that nobody can manage. That scenario is not hypothetical. The ISDN switch-off makes it a near certainty for any UK restaurant still running on legacy ISDN or PSTN telephone lines unless action is taken before 31 January 2027.
That is the date Openreach has confirmed it will permanently close the UK’s copper telephone network. After that point, ISDN and PSTN lines simply stop working. No migration path, no extension, no workaround arranged for you. The ISDN switch-off affects every business that relies on a traditional landline in any form, and restaurants are more exposed than most, because so many of the systems they depend on every day quietly use one.
This guide is designed to help restaurant owners and operators understand exactly what is at risk, how to audit their current setup, and what practical steps to take to migrate safely and on time before the ISDN switch-off deadline.
Key takeaways
- Openreach will permanently close the UK’s PSTN and ISDN network on 31 January 2027. Any system relying on a copper telephone line will stop working after that date.
- Restaurants are especially vulnerable because multiple systems, including reservation lines, card terminals, EPOS, alarms, and broadband, may depend on ISDN or PSTN without operators realising it.
- The two main migration routes for the ISDN switch-off are hosted VoIP and SIP trunking. The right choice depends on your site count, call volumes, and existing infrastructure.
- You can keep your existing phone number by porting it to a VoIP service, protecting continuity for regulars and online listings.
- Lead times for broadband upgrades and number porting mean that starting your ISDN switch-off migration now is significantly safer than leaving it until 2026.
What the ISDN switch-off actually means
The UK’s Public Switched Telephone Network (PSTN) was built over more than a century. ISDN (Integrated Services Digital Network) is a later evolution of it, but both run over the same underlying copper infrastructure. For decades, virtually every UK business phone line, broadband connection, and dial-up alarm system relied on this network. It works, but it is expensive to maintain, incapable of keeping pace with modern communication demands, and increasingly incompatible with the way businesses actually operate today.
Openreach, which owns and manages the physical network, has been signalling this change for years. The House of Commons Library briefing on the UK switch to digital landlines sets out the timeline and regulatory background clearly, confirming that the January 2027 deadline is fixed. Openreach’s official PSTN switch-off update and business migration guidance make plain that legacy line prices are already rising as the network is wound down, and that the infrastructure will be gone entirely by the deadline.
What replaces it is Voice over Internet Protocol (VoIP) and related technologies. Instead of routing calls over copper, they travel as data packets over a standard internet connection. The voice quality is at least as good, the functionality is far richer, and the cost to run is typically lower. The challenge is not the technology itself. The challenge is identifying everything in your restaurant that currently depends on the old network and replacing it in time before the ISDN switch-off takes effect.
“The network is not being paused or partially retired. On 31 January 2027, it closes. Any business that has not migrated before the ISDN switch-off deadline will lose services without warning.”
Why the ISDN switch-off puts restaurants at particular risk
Most businesses have a phone line and a broadband connection. That is straightforward enough to audit and migrate. Restaurants, however, are different in one important respect: they run a dense cluster of systems, many of which were installed years apart by different contractors, and not all of them are obviously connected to the telephone network.
A busy independent restaurant might have a reservation line, a broadband router plugged into an ADSL socket, a chip-and-PIN terminal with a PSTN fallback, an EPOS system that phones home over a landline for reconciliation, a monitored alarm system that dials the security company if triggered, and possibly a lift or fire panel with an auto-dialler built in. Each of those could be an ISDN or PSTN dependency. If even one of them is missed in a migration plan, it creates a gap that will only be discovered at the worst possible time.
The practical impact of the ISDN switch-off on a restaurant is critical. Card payments failing during service is not just inconvenient. It means turning away customers. A reservation line dropping at peak booking hours means lost covers that go to a competitor. A fire alarm that cannot dial out may affect your insurance compliance. These are not edge cases. They are the kinds of disruption that the ISDN switch-off will cause for any restaurant that does not prepare in time.
The deadline and what has already changed
It is worth being clear about where the UK sits in this process right now, because the ISDN switch-off is not a future event that has not started. It is already well underway.
Openreach began the so-called “stop sell” on new PSTN and ISDN products several years ago. That means providers have not been able to sell new lines on the legacy network in most areas for some time. If you have tried to add a new landline recently and found the options limited, that is why. The network is being actively wound down, not simply left to age.
The final, hard deadline is 31 January 2027. After that date, the physical copper network that carries PSTN and ISDN signals will be decommissioned. Ofcom’s official guidance on moving landlines to digital (VoIP) technology sets out what this means in practical terms for businesses and what protections apply during the transition period.
The key implication for restaurants is this: the closer the ISDN switch-off deadline gets, the busier migration providers become, and the longer lead times grow. Waiting until late 2026 to start the process significantly increases the risk of missing the deadline or being forced into a rushed migration during your busiest trading periods.
Step 1: audit your restaurant’s ISDN dependencies
Before you can plan a migration away from the ISDN switch-off deadline, you need a complete picture of everything in your building that relies on the telephone network. This audit is the single most important step, and it is worth doing methodically rather than from memory.
Start with your telecoms bill
Pull up your current phone and broadband bills and look at exactly what lines you are paying for. ISDN2 and ISDN30 lines will be explicitly named. PSTN lines may simply be described as “analogue” or “single line” connections. Note how many channels you have, what numbers are associated with them, and which provider supplies them. This gives you the baseline for your ISDN switch-off planning.
Walk every system in the building
Then physically walk through and identify every piece of technology that might make or receive calls, send data over a phone line, or connect to the outside world. The list to check includes the following:
Reservation and front-of-house phones
your main incoming number, any DDI lines, and any cordless handsets connected to a base unit.
Broadband router
if it connects via an ADSL or VDSL socket in the wall (a standard BT-style phone socket), it is running over PSTN infrastructure and will need to be replaced with a fibre or Ethernet-based connection.
Card payment and EPOS terminals
check whether they have a phone line connected as a primary or fallback payment route. Many older terminals do.
Intruder and fire alarm systems
most monitored alarms use a PSTN dialler to contact the monitoring centre. This is one of the most commonly missed dependencies in any ISDN switch-off audit.
Lift auto-diallers
if you have a lift with an emergency telephone, it almost certainly uses PSTN.
Background music or PA systems
some use a line to receive scheduled content updates or remote management commands.
CCTV monitoring
If your CCTV is remotely monitored by a third party, check how it sends alerts.
Document and prioritise
For each dependency you find, note who supplies it, when the contract expires, and whether the supplier has already offered a migration path. Some suppliers will have contacted you already. Others will not. Rank each dependency by the impact its failure would have on your operation: card payment failure is critical; a system that sends weekly reports over a landline is lower priority. This prioritisation shapes your ISDN switch-off migration plan.
Step 2: choose the right migration path
Once you know what you have, you can decide how to replace it. The ISDN switch-off leaves two main migration options for restaurant phone systems: hosted VoIP and SIP trunking. Both deliver calls over the internet rather than copper, but they suit different situations.
Hosted VoIP
With a hosted VoIP solution, your phone system lives entirely in the cloud. You replace your handsets with IP-compatible ones (or use a softphone app on a tablet or mobile), and calls are handled by your provider’s infrastructure. There is no on-site PBX to manage, no hardware to maintain, and features such as call queuing, voicemail to email, and call recording are typically included as standard.
For most independent restaurants and small groups, hosted VoIP is the simpler and faster route to meeting the ISDN switch-off deadline. Setup is relatively quick, upfront costs are low, and the ongoing subscription model makes it easy to add or remove lines as your business changes. If you want to see a concrete illustration of what this looks like in practice, a worked example of switching a restaurant from a landline to a VoIP phone system walks through the process for a typical hospitality operator, covering call handling for reservations and peak-hour volumes.
SIP trunking
SIP (Session Initiation Protocol) trunking connects your existing on-site PBX hardware to the public telephone network over the internet, replacing your ISDN channels with virtual equivalents. If you have already invested in a capable on-site phone system and it supports SIP, this route allows you to keep that investment while cutting the ISDN connection it currently relies on.
SIP trunking tends to suit larger restaurants, multi-site groups, or businesses with complex call flows that benefit from having a PBX on-site. It requires a Session Border Controller (SBC) to manage the connection securely, and it demands a reliable, well-provisioned internet connection to deliver consistent call quality. We can provide Direct Routing as a Service for Microsoft Teams for organisations that want to bring their voice capability inside their existing collaboration platform, which is increasingly popular with restaurant groups that already use Teams for management communication.
A note on broadband
Whichever route you choose, your internet connection becomes the foundation of everything after the ISDN switch-off. If your current broadband is delivered over a copper ADSL or VDSL line, that connection is itself a PSTN dependency and will need upgrading before the deadline. Full-fibre (FTTP) or an Ethernet leased line provides the reliability and speed that hosted VoIP and SIP trunking require. Our business connectivity solutions are designed exactly for this kind of critical-use environment, with service levels and resilience built in from the ground up.
FTTP (Fibre to the Premises)
Full-fibre broadband delivered directly to your building. Fast, consistent, and not dependent on copper for the final connection. The right choice for most single-site restaurants preparing for the ISDN switch-off.
Ethernet leased line
A dedicated, uncontended connection with symmetric upload and download speeds and a strong Service Level Agreement (SLA). Ideal for high-volume operations or multi-site groups where downtime has significant financial consequences.
SBC (Session Border Controller)
A device or software component that manages and secures SIP calls at the boundary between your internal network and the public internet. Required for SIP trunking deployments.
Step 3: Port your number and protect your identity
Your reservation phone number is a business asset. It is on your website, your Google profile, your OpenTable or ResDiary listing, printed on menus, and in the contacts list of every regular guest you have built up over the years. Losing it during an ISDN switch-off migration would be damaging in a way that is difficult to quantify but easy to feel.
The good news is that number porting is well established and fully supported across VoIP and SIP trunking services. Your existing geographic number can be moved from your current ISDN provider to your new VoIP provider, and during the porting window, calls are bridged so nothing falls through. The process typically takes between five and ten working days and, when managed carefully, is transparent to callers.
To make porting as smooth as possible, there are a few things worth doing in advance. Confirm that your number is eligible for porting (virtually all geographic 01/02 numbers are). Check your current contract for any notice period or porting restrictions. Make sure your new provider has confirmed they can accept the number before you give notice to your existing one. We handle this process end-to-end for our customers, so there is no gap in service during the switchover.
Step 4: upgrade your broadband in time
This step catches many businesses out, because broadband upgrades are not always quick. If your building requires a new fibre cabinet connection, a civils survey, or any form of wayleave agreement with a landlord, the lead time from order to live service can stretch to several months. For restaurants in older buildings, listed premises, or shared sites, this can be even more complex.
The practical advice here is simple: do not treat broadband as an afterthought in your ISDN switch-off migration plan. Start the broadband assessment at the same time as your telephony audit, not after it. That way, if a long lead time emerges, you have time to accommodate it before it becomes a problem. Running on our resilient global Voice and Data network means that once connectivity is in place, your voice services benefit from the same infrastructure resilience rather than sharing a consumer-grade connection.
Step 5: replace legacy dependencies system by system
With your audit done, your migration route chosen, and your broadband plan in place, the next step is to work through your list of PSTN dependencies and replace each one. This is best done in a sequenced order rather than all at once, so that at every point you have at least one working system to fall back on.
Phone system first
Migrate your main voice service first, since it is the most visible and has the most complex porting requirements. Once your VoIP or SIP service is live and tested, you have a working communications platform that everything else sits alongside. Getting this right early removes the biggest risk from the ISDN switch-off process.
Card terminals and EPOS next
Contact your card payment provider and EPOS supplier and ask them directly whether your terminal has a PSTN dependency and what their recommended migration path is. Many modern terminals already use IP or mobile connectivity as their primary route and simply need reconfiguring. Older hardware may need replacing. Either way, this is a conversation to have now rather than in the final weeks before the ISDN switch-off deadline.
Alarm and safety systems last, but not least
Alarms are often the most technically complex to migrate because they involve a monitoring centre as well as the on-site hardware. Your alarm company should already be aware of the ISDN switch-off and should have a migration product available. If they have not contacted you, contact them. Lift auto-diallers and fire panels may require an engineer visit to reprogram or replace the dialler module. Factor in lead times for this work when you plan your schedule.
Testing before go-live
Every migration, no matter how well planned, should include a testing phase before the old system is decommissioned. For a restaurant, the ideal time to test is during a quiet period, not before an evening service on a Saturday.
A basic test plan for restaurant telephony should confirm all of the following.
- Inbound calls reach the right handsets.
- Outbound calls connect and display the correct caller ID.
- Voicemail and any call queuing behave as expected.
- The broadband connection remains stable under load, with voice calls and EPOS traffic running simultaneously.
- Any failover or backup routing activates correctly if the primary connection drops.
Run these tests a week or two before you plan to cut over, so there is time to resolve any issues. Then run them again immediately after the cutover, while your engineer or provider is still available to respond quickly.
Why acting on the ISDN switch-off now matters more than you might think
The ISDN switch-off deadline of January 2027 is close enough that the industry is already feeling the pressure. Migration providers are busier than they were twelve months ago, and as 2026 progresses, lead times for full-fibre installs, number porting slots, and hardware delivery will lengthen. Businesses that start their ISDN switch-off preparations in 2025 or very early 2026 have real flexibility to move at their own pace and test properly. Those that leave it until autumn 2026 are likely to find themselves competing for engineer time and installation slots with thousands of other businesses in the same position.
There is also a financial dimension that is easy to overlook. Openreach has already begun increasing prices on legacy ISDN and PSTN lines as it winds the network down. Acting on the ISDN switch-off now is not just about resilience. It is also about avoiding a period of paying elevated prices for a service that is about to be switched off anyway. In most cases, a well-configured hosted VoIP service costs less per month than the equivalent ISDN line rental, even before you factor in call charges.
“Responding to the ISDN switch-off is not simply a compliance exercise. For most restaurants, it is an opportunity to replace an ageing, inflexible system with something that genuinely serves the way they work today.”
We have worked with businesses across a range of sectors through transitions exactly like this one. If you want to understand the kind of outcomes other organisations have achieved, our real-world Fuse 2 case studies give a clear picture of what well-managed migrations look like and what difference they make.
A note on multi-site restaurant groups
For groups operating multiple sites, the ISDN switch-off is both a challenge and an opportunity. A centralised cloud telephony platform means that calls can be routed intelligently across sites, overflow can be managed from a central number, and call recording and analytics are available for every location from a single dashboard. Managing this at scale, with consistent quality across sites and integrated with tools like Microsoft Teams, is where solutions such as the Anywhere365 cloud contact centre solution come into their own, particularly for groups that handle high volumes of reservation and delivery enquiries.
The ISDN switch-off migration is also easier to manage with a single partner handling all sites rather than dealing with each one separately through different local suppliers. We can explore our full range of cloud communication services with you and design a solution that fits across your estate, with a single point of contact and consistent service standards throughout.
Frequently asked questions
What is the ISDN switch-off and when does it happen?
Openreach is permanently closing the UK’s legacy PSTN and ISDN telephone network on 31 January 2027. After this date, any phone line, card terminal, EPOS system, or alarm that relies on a copper ISDN or PSTN connection will stop working. Businesses must migrate to IP-based alternatives such as hosted VoIP or SIP trunking before the ISDN switch-off deadline.
Which restaurant systems are affected by the ISDN switch-off?
Any system that uses a traditional landline connection could be affected by the ISDN switch-off. This includes your main reservation phone lines, broadband delivered over copper ADSL, chip-and-PIN or EPOS card payment terminals with a landline fallback, CCTV monitoring systems, and intruder or fire alarms that dial out over PSTN. It is worth auditing every connected system in the building, not just the obvious telephone handsets.
Can I keep my existing phone number when I switch to VoIP?
Yes. You can port your existing geographic number to a VoIP or SIP trunking service so customers and regulars can still reach you on the same number. The porting process typically takes a few working days and should cause minimal disruption if managed carefully by your provider. Do not cancel your existing line until porting is confirmed complete.
What is the difference between hosted VoIP and SIP trunking for a restaurant?
Hosted VoIP puts the phone system entirely in the cloud, meaning you need compatible IP handsets but no on-site PBX hardware. SIP trunking connects your existing on-site PBX to the public network over the internet. For most independent restaurants and small groups, hosted VoIP is simpler to deploy and maintain ahead of the ISDN switch-off. Larger multi-site groups may prefer SIP trunking for greater control and integration with existing systems.
How long does it take to migrate from ISDN to VoIP?
A straightforward single-site ISDN switch-off migration can typically be completed within two to four weeks once an audit is done and a provider is appointed. However, lead times for broadband upgrades, number porting, and compatible hardware can extend this, especially as the 2027 deadline approaches and demand on migration services increases. Starting the process now gives you the greatest flexibility and the lowest risk.
Is your restaurant ready for the ISDN switch-off?
The ISDN switch-off is one of those changes that feels distant until it is not. The January 2027 deadline is fixed, the network wind-down is already under way, and the restaurants that manage this well are the ones that start their audit now rather than waiting for a problem to force their hand.
We work closely with businesses across hospitality and beyond to make migrations like this straightforward, from the initial audit through to go-live testing and ongoing support. If you would like to understand where your restaurant stands and what an ISDN switch-off migration plan might look like, get in touch with the Fuse 2 team and we will help you build a clear picture of what needs to happen and when. You can also learn more about Fuse 2 Communications and how we approach long-term partnerships with the businesses we support.
