PSTN Switch Off UK 2027: Port Your 0800 & Freephone Number Before the Deadline

Openreach is permanently retiring the UK's analogue copper network on 31 January 2027. If your business takes calls on an 0800, 0808 or other freephone number, here's why you need to act now — and how to port it to VoIP with minimal disruption.

If your business still answers customer calls on a traditional freephone line, the countdown has already started. Openreach has confirmed there will be no further delays: every PSTN and ISDN circuit in the UK stops working on 31 January 2027, and providers can no longer sell new PSTN-based lines at all. For any business relying on an 0800, 0808 or 0500 number, that means the underlying infrastructure your number depends on is being switched off — whether or not you've made a plan.

What's actually happening to the PSTN

The Public Switched Telephone Network (PSTN) is the copper-wire infrastructure that has carried UK phone calls for well over a century, alongside ISDN, its digital-era counterpart used by many business phone systems. Openreach is retiring both permanently as the country completes its move to all-IP, fibre-based connectivity — meaning every call will eventually travel over broadband rather than copper.

The original switch-off date of December 2025 proved unworkable and was pushed back to give providers more time to safely migrate complex and vulnerable services, including telecare. That revised date — 31 January 2027 — is now treated as final.

It isn't only desk phones affected. Alarm systems, lift emergency lines, card payment terminals and telecare pendants that still run over a traditional phone line all sit on the same clock. Ofcom's own reporting has also flagged a sharp rise in PSTN service outages as the ageing copper network becomes less reliable in the run-up to shutdown — so for many businesses this is no longer just a compliance date, it's a business continuity risk.

Why freephone and 0800 numbers are especially exposed

Many UK businesses assume their 0800 or freephone number is somehow separate from this transition — it isn't. A freephone number is a non-geographic number that gets routed to your business; if that routing still runs through a PSTN or ISDN trunk, or through a legacy provider that hasn't upgraded its own core network, your number is exposed to exactly the same cut-off date.

This matters more for inbound freephone traffic than for almost any other line type, because 0800 and 0808 numbers exist specifically to remove friction for callers — since the 2015 Ofcom “UK Calling” reforms, calls to 0800 and 0808 numbers have been free from any UK landline or mobile. That's a number your customers, suppliers and partners have memorised, printed on vans, embedded in ad campaigns and saved in their phones. Losing it, or having it go down unexpectedly, is a far bigger commercial hit than losing a standard landline extension.

The Ofcom porting mandate — your right to keep your number

Number portability in the UK isn't a courtesy offered by providers — it's a regulatory requirement. Ofcom's powers to mandate portability come from the Communications Act 2003, and the detailed rules providers must follow sit in General Condition B3 (Number Portability) and General Condition C7 (Switching). In practice, this means:

• Non-geographic numbers, including the 03 and 08 ranges that cover UK freephone and toll-free numbers, are portable between authorised providers.
• Your existing provider cannot simply refuse to release your number when you switch, outside a narrow set of technical exceptions.
• Your new provider handles the porting request on your behalf once you've signed a Letter of Authority (LOA).
• Ofcom can enforce against providers that breach these switching and portability conditions.

In other words, if you're holding back from migrating off the PSTN because you're worried about losing your published 0800 number, that concern shouldn't be what's stopping you — the regulatory framework is built to protect exactly that.

How to port a UK 0800 or freephone number to VoIP

Whether you're planning to port a UK toll-free number, port an 0800 number in the UK, or port a UK freephone number from an existing VoIP provider, the process itself follows the same basic path:

1. Check your current setup Identify the exact number range (0800, 0808 or 0500), your current provider, and whether the number currently runs over PSTN, ISDN, or an existing VoIP trunk that simply needs moving.
2. Choose an Ofcom-compliant VoIP provider Pick a cloud communications provider set up to handle UK freephone porting and ongoing call routing — not just a generic VoIP reseller.
3. Sign a Letter of Authority (LOA) This is a short signed document authorising your new provider to request the transfer of your number from your existing (losing) provider on your behalf.
4. Your new provider submits the port request The request goes through the standard industry porting process between your losing and gaining providers — you don't need to manage this directly.
5. A port date and time window is confirmed Most single business number ports complete within roughly 10–14 working days, and the actual cutover window is typically a matter of minutes.
6. You go live on VoIP Calls to your freephone number now route over your new cloud platform — to desk phones, mobiles, softphones or call centre agents — fully independent of the PSTN.

Don't have a freephone number yet? Here's how to get one

Plenty of businesses reading this aren't porting an existing number at all — they're weighing up whether to get a UK freephone number for the first time, precisely because now is the moment they're re-platforming onto VoIP anyway.

If that's you, getting started is simpler than porting, because there's no losing provider or LOA to coordinate:

• Pick your number range — 0800 and 0808 for freephone (free to call from any UK landline or mobile), or a memorable 0800 sequence if you want something brandable.
• Choose a plan that matches your call volume — UKTollFree Starter starts from £14.99/mo; Business adds IVR, recording and analytics.
• Go live quickly — since there's no existing number to migrate, a brand-new UK freephone number can typically be issued after a short demo confirmation.
• Route calls anywhere — to a UK office, a distributed remote team, or internationally, since your number lives on the cloud platform rather than a physical exchange.

What happens if you do nothing

Doing nothing isn't a neutral choice — it's a decision to let the deadline choose your migration date for you. Based on what's confirmed so far:

• Legacy PSTN and ISDN line rental is rising in steps through 2026, ahead of the network actually switching off.
• Businesses that haven't migrated risk being defaulted to a bare-bones, emergency-only fallback service with no normal inbound or outbound calling.
• As the January 2027 deadline approaches, provider capacity to handle migrations gets squeezed — the businesses that leave it latest get the least support and the least choice.
• An unplanned, forced cutover carries a real risk of your freephone number being unreachable during the transition, at exactly the point your customers are trying to call you.

None of this is a reason to panic — there's still runway before January 2027. But it is a clear reason to start the process now, on your own terms, rather than under pressure later.

Why UK businesses port with UKTollFree

UKTollFree.com (operated by Aancall LLC) is built around UK Freephone numbers — 0800 and 0808 — for businesses that need their freephone line to keep working as the PSTN is retired.

• Porting support via a short demo — LOA and provider coordination handled for you
• Plans from £14.99/mo with transparent overage
• Cloud routing to mobiles, landlines, softphones and teams anywhere
• IVR, call recording and analytics on Business plans
• Ofcom Freephone ranges — free for UK callers from mobiles and landlines

Frequently asked questions

Can I port my UK 0800 number to a new provider?

Yes. Freephone and other non-geographic UK numbers are fully portable under Ofcom's number portability rules, so switching provider or switching to VoIP doesn't mean losing your number.

What is the deadline for the UK PSTN switch off?

Openreach's confirmed end-of-life date for PSTN and ISDN services is 31 January 2027. The original December 2025 date was extended to allow more time for complex and vulnerable migrations.

Will porting my 0800 number cause downtime?

In most cases, no. Ports are scheduled for a specific date and time window, and the large majority complete with only a few minutes of interruption, or none that callers notice.

Are 0800 and 0808 numbers free for callers?

Yes. Calls to 0800 and 0808 numbers have been free for callers from any UK landline or mobile since the 2015 Ofcom UK Calling rules. The business that owns the number pays for inbound calls — see are 0800 numbers free? and who pays for 0800 calls.

How long does it take to port a business number in the UK?

A standard business number port typically takes around 10 to 14 working days once a completed Letter of Authority has been submitted, though this can vary by losing provider and number type.

Final thoughts

The PSTN switch-off is a fixed deadline, not an optional upgrade. If your 0800 or freephone number still depends on copper or ISDN infrastructure, start the port while you still have time for a controlled cutover — and keep the number your customers already know.

This article is for general information and does not constitute legal or regulatory advice. For the latest official guidance on the PSTN switch-off, refer to Ofcom and Openreach directly.