The UK’s traditional telephone network is being switched off permanently.

By 31 January 2027, the old copper-based analogue PSTN (Public Switched Telephone Network) and ISDN (Integrated Digital Services Network) services will no longer operate. Any business still relying on these services, directly or indirectly, will need to move to modern digital alternatives.

Below are the most common questions we hear from business owners, from the very basic to the more technical.

What is the PSTN and ISDN switch-off?

The UK’s old telephone network is being retired and replaced with modern digital services that use internet connectivity instead of copper phone lines.

When is the PSTN switch-off happening?

The current nationwide deadline is 31 January 2027.

Is the telephone network actually being switched off?

Yes.

Millions of lines have already been migrated, Openreach stopped selling new PSTN and ISDN services in 2023, and the old network is actively being retired.

Will my business phones stop working?

If your phone system still relies on PSTN or ISDN services, then yes, it will eventually stop working unless it is upgraded.

Will my phone number change?

Usually not.

In most cases, your existing business telephone numbers can be transferred to your new digital phone system.

Can I keep my existing phone handsets?

Sometimes.

Some modern handsets can continue to be used, while older equipment may need replacing.

Do I need to replace all my office cabling?

Usually not.

Most businesses can migrate without major building work or rewiring.

Is the telephone network switch-off a scam?

No.

This is a genuine nationwide telecommunications programme affecting businesses and households across the UK.

Do I legally have to switch to a digital phone system?

You are not being forced by law to switch, but the old network is being permanently retired. If you currently use PSTN or ISDN services, you will need to move to an alternative service before they are withdrawn.

Can I just wait until 2027 to make the switch?

You can, but it is unlikely to be the best option.

Waiting increases the risk of higher costs, limited availability of engineers, longer lead times and potential disruption to your business.

Common Business Questions

We don’t use landlines anymore. Does this affect us?

Possibly.

Many businesses no longer make calls using traditional phone lines but still have critical systems that rely on them.

Examples include:

• Alarm systems
• Fire alarms
• CCTV monitoring
• Lift emergency phones
• Door entry systems
• Card payment terminals
• Broadband services

How do I know if my business is affected?

If you have equipment connected to a telephone socket or traditional phone line, it should be checked.

Many businesses are surprised to discover that systems they rarely think about still rely on PSTN services.

Will my broadband stop working?

Not necessarily.

However, some broadband services rely on an underlying PSTN line and may need to be migrated to a digital-only service.

Will my alarm still work after the switch-off?

Not all alarms will.

Many older intruder alarms and monitored alarm systems use analogue phone lines to communicate with monitoring centres.

These systems should be assessed before the switch-off.

Will my CCTV be affected?

Potentially.

Older CCTV systems that use telephone lines for remote monitoring or alerting may require upgrading.

Will my card payment machine still work?

Some older payment terminals use traditional phone lines.

If yours does, it may need to be replaced or reconfigured before the switch-off.

What happens if I do nothing?

At best, you’ll face increasing costs.

At worst, critical business systems could stop functioning when the services they rely on are withdrawn.

Why are Openreach switching off the network?

The infrastructure is reaching the end of its life.

Much of the equipment supporting PSTN and ISDN services is decades old, difficult to maintain and no longer supported by manufacturers.

Is it more expensive to keep old phone lines?

Yes.

Openreach has significantly increased wholesale charges for many legacy services to encourage migration to modern alternatives.

More Technical Questions

What is replacing PSTN and ISDN?

Most businesses are moving to:

• VoIP (Voice over Internet Protocol)
• SIP-based communications
• Cloud-hosted telephone systems
• Full-fibre and Ethernet connectivity

What is VoIP?

VoIP stands for Voice over Internet Protocol.

Instead of using a traditional phone line, voice calls travel securely over your internet connection.

What is SIP?

SIP (Session Initiation Protocol) is a technology that allows voice communications to be delivered over data networks.

Many organisations that previously used ISDN are moving to SIP-based services.

Will digital phones work during a power cut?

Unlike traditional phone lines, digital services rely on local power and internet connectivity.

Businesses with critical communication requirements should consider battery backup, UPS systems and business continuity planning.

Can I migrate in stages?

Yes.

In fact, a phased migration is often the safest approach, allowing critical systems to be upgraded with minimal disruption.

What are the benefits of moving to a digital phone system?

Businesses often gain:

• Hybrid and remote working capability
• Mobile and desktop calling apps
• Auto attendants and call queues
• Voicemail-to-email
• Better call quality
• Easier scalability
• Lower long-term costs
• No expensive maintenance contracts
• Easy to manage and make changes

How long does a migration to VoIP system take?

This depends on the size and complexity of your business.

A simple phone system migration may take days, while larger projects involving multiple sites, alarms, connectivity and security systems may require more detailed planning.

What Should My Business Do Next?

The best starting point is a full audit of your communications and connected systems.

This should include:

• Telephone lines
• Internet connections
• Alarm systems
• CCTV systems
• Payment terminals
• Door entry systems
• Lift communications
• Any other equipment connected to a phone line

The earlier you identify potential issues, the easier and more cost-effective the migration will be.

Need Help Preparing for the PSTN and ISDN (telephone network) Switch-Off?

Don’t wait until the last minute and risk rising costs, limited engineer availability or unexpected downtime.

At Intrasource, we help businesses identify hidden dependencies on PSTN and ISDN services, plan their migration and move to modern digital communications with minimal disruption.

Book Your Free Telephone Network Switch Off Impact Assessment

We’ll review your phone systems, connectivity, alarms, payment terminals and other critical services to identify exactly what needs attention before the 2027 deadline.

Contact us today and ensure your business is ready long before the switch-off arrives.