PSTN Switch Off at a Glance

Question	Answer
What is PSTN?	The Public Switched Telephone Network used for traditional landline voice services
When is PSTN being switched off?	31 January 2027
Who is affected?	Businesses and consumers still using services that depend on the UK’s legacy network
What replaces PSTN?	Digital, IP-based services such as VoIP and digital voice
Is ISDN also affected?	Yes
Are traditional analogue phone lines affected?	Yes
Are alarms and telecare affected?	Potentially, depending on the equipment and connection
Are lift emergency phones affected?	Potentially
Does every business need a new phone system?	No. It depends on what your existing system uses
Can I keep my existing number?	In many cases, yes, through number porting
What happens if I do nothing?	Your provider may migrate you to a replacement service, but affected services and equipment may not work correctly unless they are compatible

What is the PSTN?

PSTN stands for Public Switched Telephone Network.

It is the telephone network that has historically connected landline calls.

For decades, businesses could plug a telephone into a wall socket and make calls through a copper telephone line connected back through the local telephone exchange.

This technology has served the UK for generations, but it is now legacy equipment that is not fit for purpose.

Much of the infrastructure and equipment supporting traditional analogue services was designed and installed decades ago. Maintaining it is becoming increasingly difficult and expensive, while modern communications have moved towards IP-based technology.

The PSTN is therefore being replaced by digital communications networks.

What is the PSTN Switch Off?

The UK is in the middle of one of the biggest changes to its telecommunications infrastructure in decades.

The Public Switched Telephone Network (PSTN), the traditional network that has supported analogue landline telephone services for decades, is being retired and replaced by modern digital, IP-based communications.

Openreach’s legacy PSTN network is scheduled to be retired by 2027, with customers being moved away from traditional PSTN and associated Wholesale Line Rental (WLR) services.

For most people, the change will simply mean their traditional telephone service is replaced with a digital equivalent. But for businesses, the PSTN switch off can be much more significant.

That’s because a telephone line isn’t necessarily just being used to make telephone calls.

The same connection could be support:

• Business telephone systems
• Broadband
• Fax machines
• Alarm systems
• CCTV
• Payment terminals
• Lift emergency phones
• Door entry systems
• Telecare equipment
• Modems
• EPOS equipment
• Building management systems
• Monitoring equipment
• Intercoms
• Other machine-to-machine communications

Rather than voice calls being carried using the traditional circuit-switched telephone network, modern services use Internet Protocol (IP) technology.

When is the PSTN Switch Off?

The key UK deadline is:

31 January 2027

Openreach has confirmed that its PSTN network will be retired by this date.

However, it’s important to understand that there isn’t necessarily one single day when every business in the UK wakes up and loses its analogue line.

The migration is taking place progressively, with different providers, locations and customers are being moved at different times.

Your own migration date may therefore be earlier than January 2027.

This is particularly important for businesses because waiting until the final deadline could leave you with limited time to:

• Audit your services
• Replace incompatible equipment
• Port telephone numbers
• Install new connectivity
• Configure a new phone system
• Test alarms
• Test payment systems
• Arrange engineer visits
• Resolve installation problems
• Train employees

The deadline is 31 January 2027, but your preparation should start well before then.

Why is the PSTN Being Switched Off?

There are several underlying reasons for the change in equipment, including:

The Network Is Ageing

The PSTN has been in service for decades and the technology supporting it is increasingly difficult to maintain.

Equipment and replacement parts are becoming harder to source.

As the infrastructure ages, maintaining the network becomes more expensive and faults become more difficult to resolve.

Modern Networks Are IP-Based

The telecommunications industry has moved towards digital, IP-based infrastructure.

Voice, video, messaging and data can all be delivered using IP networks, providing a more flexible foundation for modern communications.

Businesses Need More Than a Telephone Line

Traditional telephone lines were designed primarily around voice communication.

Modern businesses expect much more.

They want:

• Video calling
• Mobile working
• Instant messaging
• CRM integration
• Call analytics
• Call recording
• Call routing
• Presence information
• Collaboration
• Disaster recovery
• Flexible working

Digital communications platforms can support these requirements much more effectively.

What Is ISDN and Why Is It Being Switched Off?

Another term you’ll frequently encounter alongside PSTN is ISDN.

ISDN stands for Integrated Services Digital Network.

Unlike PSTN, ISDN is digital rather than analogue, but it is still part of the legacy telephone infrastructure being retired.

Businesses historically used services such as ISDN2 and ISDN30.

ISDN allowed organisations to run multiple simultaneous telephone calls and connect traditional business telephone systems to the public network.

For many businesses, ISDN was the standard way of connecting a traditional on-premise PBX (Private Branch Exchange) to the telephone network.

But ISDN is now being replaced by IP-based technologies such as SIP trunking and hosted VoIP.

If your business has an older PBX with ISDN connections, the PSTN switch off is therefore likely to require more planning than simply changing a handset.

What Replaces PSTN?

There isn’t one universal replacement for every customer.

The right solution depends on what you’re currently using the PSTN for.

VoIP

Voice over Internet Protocol (VoIP) carries telephone calls over an IP network rather than a traditional telephone network.

A modern hosted phone system can provide considerably more functionality than a traditional telephone line.

Features can include:

• Auto attendants
• Call queues
• Call recording
• Call routing
• Mobile apps
• Desktop softphones
• Voicemail
• Call analytics
• CRM integration
• Business hours
• Hunt groups
• Geographic numbers

SIP Trunking

SIP stands for Session Initiation Protocol.

SIP trunking can replace traditional ISDN connections by connecting a business telephone system to the public telephone network over an IP connection.

This can be particularly useful for businesses that already have a relatively modern IP-capable PBX and don’t necessarily want to replace the entire phone system.

Hosted VoIP

Hosted VoIP moves much of the telephone system into the cloud.

Instead of owning and maintaining a traditional PBX on your premises, the phone system is hosted by the provider.

This can make it easier to:

• Add users
• Remove users
• Support remote workers
• Manage multiple offices
• Route calls
• Integrate CRM systems
• Monitor performance
• Introduce new features

For many small and medium-sized businesses, hosted VoIP is one of the most straightforward alternatives to a traditional PSTN or ISDN-based telephone system.

What Devices Could Be Affected by the PSTN Switch Off?

It’s likely that businesses will believe they don’t have a PSTN dependency because it has already moved its telephone system to VoIP.

But there could still be legacy equipment elsewhere in the building.

Potentially affected equipment includes:

Telephone Systems

• Analogue phones
• Legacy PBXs
• ISDN phone systems
• DECT systems connected to analogue lines
• Emergency phones

Security Systems

• Intruder alarms
• Fire alarms
• CCTV
• Remote monitoring systems
• Access control
• Door entry systems

Safety Equipment

• Telecare
• Personal alarms
• Emergency call systems
• Lift emergency phones

Payment and Retail Equipment

• Card terminals
• EPOS systems
• Payment gateways
• Transaction terminals

Other Equipment

• Fax machines
• Modems
• Metering equipment
• Building management systems
• Monitoring equipment
• Industrial machinery
• Legacy remote-access systems

What Will the PSTN Switch Off Cost?

The cost depends entirely on what you’re replacing.

For a business with one traditional telephone line and one basic handset, migration may be relatively straightforward.

For a business with multiple locations, an ISDN PBX, alarm systems, lift lines and several legacy devices, the project can be considerably more involved.

A better way to calculate your PSTN migration cost is to create an inventory.

Service	Current Technology	Replacement	One-Off Cost	Monthly Cost
Main phone	PSTN	Hosted VoIP	£	£
Alarm	PSTN	4G/IP	£	£
Lift	PSTN	4G/IP	£	£
Broadband	ADSL/FTTC	FTTP/SOGEA	£	£
Card terminal	Analogue	Ethernet/4G	£	£
Fax	PSTN	Digital alternative	£	£
Backup	None	4G/5G	£	£

This gives you a much more realistic total cost of migration.

What Happens If You Do Nothing?

The outcome depends on your provider, service and equipment.

Some providers may migrate customers onto replacement digital services.

In some cases, protective migration programmes may be used.

However, if a legacy service or connected device cannot be migrated automatically, you could face service disruption.

Potential consequences include:

• Telephone service changes
• Loss of analogue functionality
• Incompatible equipment
• Alarm communication failures
• Lift communication failures
• Payment terminal problems
• Broadband changes
• Increased costs
• Emergency communications issues
• Loss of business continuity

The best thing to do is get in contact with your providor and confirm whether the PSTN and ISDN switch off will affect you.

It’s best to act sooner rather than later since legacy WLR services are becoming increasingly expensive as the industry approaches closure.

Openreach announced a series of price increases for legacy WLR products during 2026, with the stated aim of encouraging migration to newer digital services.

In other words, delaying the migration doesn’t necessarily save money.

A PSTN Switch Off Audit Checklist for Businesses

Before migrating, work through the following checklist.

Step 1: Identify Every Legacy Line

Find out how many:

• PSTN lines
• Analogue lines
• ISDN2 lines
• ISDN30 lines
• Legacy broadband services

you currently have.

Step 2: Identify Every Telephone Number

Record all numbers and what they are used for.

Step 3: Identify Every Connected Device

Check:

• Phones
• PBXs
• Alarms
• Fire alarms
• CCTV
• Lifts
• Payment terminals
• Door entry
• Fax
• Telecare
• Modems
• Monitoring systems

Step 4: Identify Your Current Contracts

Check:

• Contract end dates
• Renewal dates
• Cancellation periods
• Early termination charges
• Equipment ownership

Step 5: Check Connectivity Availability

Find out whether you can receive:

• FTTP
• Business fibre
• SOGEA
• 4G
• 5G
• Fixed wireless
• Other alternatives

Step 6: Choose Your Replacement Technology

Decide whether you need:

• Hosted VoIP
• SIP
• New PBX
• Digital voice
• Fibre
• 4G/5G backup
• Replacement alarm communications

Step 7: Test Critical Equipment

Do not assume compatibility, test it.

Step 8: Plan Number Porting

Make sure important telephone numbers are retained.

Step 9: Plan for Power Failure

Consider UPS and battery backup.

Step 10: Complete the Migration

Only cancel legacy services once the replacement is working and tested.

The 90-Day PSTN Switch Off Action Plan

If you haven’t started yet, don’t panic, but don’t leave it until the final weeks either.

Days 1–30: Audit

Create a complete inventory of your connectivity and telephone services.

Identify every PSTN and ISDN dependency.

Speak to your provider.

Days 31–60: Design

Choose your replacement connectivity and communications systems.

Get quotations.

Confirm equipment compatibility.

Plan number porting.

Days 61–75: Install

Install the new connectivity and telephone systems.

Replace incompatible equipment.

Configure failover.

Days 76–90: Test

Test:

• Incoming calls
• Outgoing calls
• Emergency calling
• Number presentation
• Call routing
• Alarms
• Lift phones
• Payment systems
• Door entry
• Remote monitoring
• Power failure procedures

Only once everything has passed testing should the legacy services be cancelled.

PSTN Switch Off FAQs

Is the PSTN switch off definitely happening?

Yes. Openreach has reaffirmed the retirement of its PSTN network by 31 January 2027.

What is the PSTN switch off date?

The key UK deadline is 31 January 2027, although individual customers are being migrated before this date.

Will my landline stop working?

If you currently rely on a legacy analogue service, it will need to be migrated to a digital alternative.

Do I need to buy a new phone?

Not necessarily. Depending on your service and equipment, an existing handset may be usable with an appropriate digital adapter or phone system.

Is ISDN being switched off too?

Yes. ISDN2 and ISDN30 are legacy technologies being replaced by IP-based alternatives.

Is ADSL being switched off?

ADSL and other legacy broadband services are part of the wider move away from legacy networks, but the exact treatment of copper broadband services varies by product and location. Check your specific service rather than assuming every copper connection disappears on 31 January 2027.

Will I lose my telephone number?

Not necessarily. Numbers can often be ported to a replacement provider or VoIP service.

Will my alarm still work?

It may, but this must be confirmed with the alarm manufacturer or monitoring provider. Do not assume an analogue alarm will work correctly over a digital voice service.

Will my lift emergency phone still work?

It depends on the lift communication system. Contact your lift maintenance or emergency communications provider and arrange testing after migration.

Will telecare still work?

Some telecare equipment requires upgrading or replacement to work reliably on digital networks. Tell your phone provider and telecare provider that you use telecare before migration.

Will my phone work during a power cut?

Digital landline services generally require local power, unlike some traditional analogue handsets. If you depend on a landline for emergency calls, ask your provider about power backup.

Can I use 4G or 5G instead of fibre?

Yes. 4G and 5G can be used as a primary or backup connectivity solution where suitable coverage is available.

Do I have to move to VoIP?

If you want to continue using a fixed telephone service after PSTN retirement, you will need to use a digital/IP-based replacement. VoIP is one of the main options, but the precise service may vary by provider.

Can I keep my existing phone number with VoIP?

In many cases, yes. Ask your provider about number porting before cancelling your existing service.

What happens if I ignore the PSTN switch off?

Your provider may migrate your service or offer a replacement, but you should not rely on this to protect every connected device. Unsupported equipment could stop working, and you may face increased costs or limited migration options.

Is the PSTN switch off only a problem for large businesses?

No. A small business with one analogue line can still be affected, particularly if that line supports an alarm, payment terminal, fax or other critical device.

How much will PSTN migration cost?

There is no universal cost. It depends on your current telephone system, connectivity, number of lines, equipment and replacement requirements.

Should I switch now or wait?

For most businesses, planning early is the safer approach. It gives you time to compare providers, test equipment, retain numbers and resolve problems before the deadline.