The PSTN & ISDN switch-off is here. Is your business ready?
BT Openreach is switching off the UK’s old copper phone network. Every business running on PSTN or ISDN lines must migrate to a cloud or IP-based phone system — or lose their phone lines entirely. Curo IP makes the migration simple, fast, and fully managed.
What is the PSTN switch-off?
PSTN stands for Public Switched Telephone Network — the traditional copper wire phone network that has connected UK businesses since the 1800s. ISDN (Integrated Services Digital Network) is the digital version that became standard in the 1990s.
BT Openreach announced in 2019 that it would switch off PSTN and ISDN entirely by January 2027, with a full stop-sell already in effect. This means:
• No new PSTN or ISDN lines can be ordered
• All existing lines will stop working when the switch-off is completed
• Businesses that don’t migrate will lose phone service with no warning
The replacement is IP telephony (VoIP) — calls made over a broadband internet connection rather than the old copper network.
Frequently asked questions
Got questions? We've got answers.
When is the PSTN switch-off date?
The full PSTN and ISDN switch-off is scheduled for December 2027 across the UK. However, Openreach has been progressively switching off exchanges since 2023 and some areas have already completed the transition. You may lose service before the national deadline if your local exchange is upgraded first.
Does the switch-off affect my broadband?
No — the switch-off only affects traditional voice lines (PSTN and ISDN). Your broadband connection runs over a separate network. However, if you have a phone line bundled with your broadband (such as BT or Sky), you may receive a migration letter from your provider.
Can I keep my existing phone numbers?
Yes. Your existing geographic numbers (01, 02) and non-geographic numbers (03, 08) can be ported to Curo IP’s cloud platform. We handle the entire porting process — your numbers stay the same, only the underlying technology changes.
How long does migration take?
Most businesses are fully migrated and live on Curo IP within 3–5 working days. Number porting takes between 5–15 working days depending on your current provider. We can set up your new system in parallel so there’s no period without phone service.
What about my fax machine, door entry, or alarm system?
Devices that use analogue phone lines — fax machines, door entry buzzers, CCTV diallers, lift emergency phones, and some card payment terminals — will also need to be addressed. Curo IP can advise on replacements for each. Modern equivalents exist for all of these over IP.
What's the difference between VoIP and hosted telephony?
VoIP (Voice over Internet Protocol) is the technology — it means voice calls travel over your internet connection. Hosted telephony (or UCaaS) is the service model — where a provider like Curo IP manages the phone system infrastructure on your behalf, so you don’t need to buy or maintain any hardware beyond handsets.
Will VoIP call quality be as good as my current phone line?
With a reliable broadband connection, VoIP call quality is equal to or better than traditional PSTN. Curo IP uses HD voice codecs and dedicated UK-hosted infrastructure. We recommend a minimum 5 Mbps upload speed per concurrent call.
Do I need to buy new hardware?
Not necessarily. Many modern IP desk phones are compatible with Curo IP, and all users get a free mobile and desktop softphone app. If you do need new handsets, Curo IP hardware starts from [price] per device.
What happens if I do nothing?
When Openreach switches off your local exchange, your phone lines will stop working. You’ll lose inbound and outbound calls, fax capability, and any other services running over that line — with no grace period. The risk of doing nothing increases significantly from 2025 onwards as the switch-off accelerates.
How much does migrating to Curo cost?
Most businesses save money on migration. VoIP calling is significantly cheaper than ISDN line rental, and Curo IP plans include free onboarding and number porting. We’ll provide a full cost comparison against your current phone bill as part of the free migration assessment.