Inreach Group · Inreach Comms · The ISDN Switch-Off

The ISDN Switch-Off.

On 31 January 2027, the UK’s copper phone network is switched off for good. Openreach has confirmed there will be no further extension. Here is what it affects, what it costs to wait, and how we move you across.

About the switch-off

What is the ISDN switch-off?

The ISDN switch-off is the retirement of the UK’s traditional copper telephone network. ISDN and PSTN lines, the physical copper connections that have carried business calls for decades, stop working on 31 January 2027. Anything that depends on them needs to move to a digital service running over an internet connection before that date.

You will see it called several things: the PSTN switch-off, the landline switch-off, the big switch off. They all describe the same thing.

iNREACH GROUP · ISDN SWITCH-OFF

The date has moved once already, from December 2025, which is why plenty of businesses stopped paying attention. Openreach has since confirmed the January 2027 date is fixed, with the remaining technical obstacles around telecare users resolved. Around 1.5 million lines are still on copper, roughly 350,000 of them at business premises.

Switch-off date

from January 31, 2027

New lines stopped

Since 2023

Lines still on copper

1.5M, UK-wide

The dates that matter now

The timeline, and what it costs to wait.

Already in place

New ISDN and PSTN lines stopped being sold nationally in 2023. If you are still on copper, you cannot order more of it.

Already in place

New ISDN and PSTN lines stopped being sold nationally in 2023. If you are still on copper, you cannot order more of it.

1 April 2026

Openreach raised legacy line rental by 20%.

1 April 2026

Openreach raised legacy line rental by 20%.

1 July 2026

A further 40% rise.

1 July 2026

A further 40% rise.

1 October 2026

A final 40% rise, taking legacy line rental to roughly double what it was in 2025.

1 October 2026

A final 40% rise, taking legacy line rental to roughly double what it was in 2025.

31 January 2027

The network is switched off. Services still running on copper stop working.

31 January 2027

The network is switched off. Services still running on copper stop working.

The price rises are deliberate. Openreach has been open about wanting to make staying on copper more expensive than moving off it, and for many businesses the digital service is already the cheaper of the two.

The other thing that changes quietly is support. As the network winds down, the engineers who know it and the parts that fix it both become harder to find. A copper fault in late 2026 will not be attended to the way it would have been five years ago.

Beyond your phones

More than your phones runs on those lines.

This is the part that catches businesses out. A copper line does more in most buildings than carry phone calls, and the things attached to it rarely sit on anyone’s IT list. Worth checking whether any of these are still on a copper connection:

  • Lift emergency phones
  • Fire alarm panels and autodiallers
  • Intruder alarms and door entry systems
  • Card payment terminals
  • Telecare and personal alarms
  • Fax lines
  • ADSL and FTTC broadband

ADSL and FTTC broadband go the same way as the phone lines, so a business that has already moved its phones to the cloud can still have a connection that stops working. If you are not certain what is connected to what, that is exactly what a line review establishes. We will go through what you are paying for, what each line actually does, and what needs replacing.

Not sure what your business still has running on copper? Book a line review and we will tell you.

Option 2

Tell us what’s in the comms cupboard.

We’ll tell you honestly which way round it should be — new cloud system or keep what you have.

Once you move, your phone system runs over your internet connection instead of a physical line. Your numbers come with you. Your team can work from a handset on a desk, an app on a laptop or a mobile, which the old network could never do.

Every system we supply is switch-off compliant, so moving now future-proofs your business rather than solving a problem twice. We design, install and support our own hosted phone system, iNTALK, entirely in-house from Milton Keynes, and we supply other platforms too where one suits you better. Because the iNTALK contract is ours, we can change your setup partway through the term rather than working around a third party’s terms.

Before anything is installed we check your internet connection is up to the job, because a cloud phone system is only as good as the line underneath it. Where it is not suitable, we will tell you, and we can put the right connection in as part of the same move.

The fair question about moving your phones onto your internet connection is what happens when that connection fails. On copper, the phones were separate. Now they are not.

The answer is failover. We supply 4G and 5G connections that take over automatically if your main line drops, so calls, card payments and cloud systems keep running while the fault is fixed. For a business that trades on the phone, it costs very little against an hour of silence.

It is also the answer where fibre has not reached you yet. 4G, 5G and leased lines all carry a phone system perfectly well, and we will tell you honestly which is realistic where you are.

Moving providers sounds disruptive. Done properly, you barely notice it.

We handle the whole switching process: dealing with your current provider, porting your numbers, and agreeing the changeover date. The honest caveat is timing, because porting depends partly on the provider you are leaving and on Openreach releasing the numbers. We quote the earliest realistic date rather than a promise nobody controls, and keep you informed throughout.

One practical warning, whoever you move with: never cancel your existing line before the port completes. Cancel first and the number can be lost rather than transferred. That is also the argument for starting now rather than in December. Porting takes as long as it takes, and everyone still on copper will be trying to move through the same window.

Once you are across, support works the way it does for everything else we do. You call us and our team answers centrally from our Milton Keynes office. Most issues are resolved on that call through phone and remote support. Nothing is passed to a third party and nothing goes abroad.

You will have a dedicated account manager from day one, with regular account reviews at whatever frequency suits you. Six weeks after installation, someone outside your account team calls to check you are happy with everything.

Not every business needs to replace everything. If you’ve invested in an on-premise phone system recently and it still does what you need, SIP trunking is the route that keeps it.

SIP replaces the ISDN lines running into your existing system with a connection over the internet. The system stays where it is, your handsets stay on desks, your numbers come with you, and the thing that was going to stop working in January 2027 is dealt with. For a business with a capable system partway through its life, it’s often the sensible answer.

Where it makes less sense is when the system itself is coming to the end of its useful life. At that point you’re spending money keeping something going that you’ll replace before long anyway, and moving to a cloud system does more for you. We supply both, and which one we recommend depends on what you already have rather than what we would rather sell.

Case Study

Cloud Telephony Transformation For a UK Legal SERVICES fIRM.

A large UK conveyancing firm with an end-of-life phone system and no hybrid working capability. iNREACH Comms deployed a 500-user hosted VoIP platform across six UK sites – zero days of downtime.

500

Users Deployed

6

UK Sites

7yr

Compliant Call Recording

0

Days of Downtime

Frequently Asked Questions

Common questions about The ISDN Switch Off.

BT is withdrawing its ISDN (Integrated Services Digital Network) and PSTN (Public Switched Telephone Network) services on January 31, 2027. From that date, traditional telephone lines will no longer work. Any business still using ISDN or PSTN for phone calls, broadband or other services will need to have migrated to a digital alternative before that date.

There are two main options. SIP trunks replace your ISDN lines with an internet-based connection while keeping your existing on-premise phone system. Hosted telephony moves your entire phone system to the cloud — removing on-site hardware and replacing it with a per-user cloud service. iNREACH can advise on which is right for your business.

Yes. Your existing phone numbers can be ported to the new system as part of the migration. We manage the porting process end-to-end — co-ordinating with your current provider, agreeing a porting date, and testing before the cutover. Your callers notice nothing.

A straightforward SIP migration for a small business typically takes two to four weeks from survey to cutover. Larger or more complex migrations — multiple sites, custom call routing, hosted telephony deployment — are scoped individually. Starting early gives you the most flexibility on timing.

After January 31, 2027, BT will no longer support ISDN or PSTN lines. Services will stop working, with no guarantee of emergency support to restore them. Businesses that leave migration too late risk being without working phones — potentially for an extended period if installation slots are fully booked.

Both options are typically cheaper than ISDN in ongoing running costs. SIP trunks significantly reduce line rental compared to ISDN channels and offer free or low-cost calls between sites. Hosted telephony removes hardware maintenance costs and scales per user. We provide a cost comparison as part of our recommendation.

CONTACT US.

For sales & general enquiries please email enquiries@inreachgroup.co.uk or call 0330 053 8180 or submit your details:

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0330 053 8180

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0330 053 8181

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