What does the PSTN switch-off mean for my business phone lines and broadband?

The short answer: the UK's old copper phone network (the PSTN) is being switched off, with an end date of 31 January 2027. Any business phone line, ISDN line or broadband that still relies on it has to move to a digital service before then. You can usually keep your phone numbers, but you need to act now, not in January.

What's actually changing

Openreach and BT are withdrawing the traditional analogue phone network, along with Wholesale Line Rental (WLR), the product most providers use to sell old-style phone lines. In practice that means:

• Analogue phone lines stop working.
• ISDN2 and ISDN30, the digital lines many older office phone systems use, are going too.
• Broadband that needs a phone line has to change. That includes old ADSL broadband and FTTC broadband that sits on a phone line. These move to SOGEA (broadband without a phone line) or to full fibre.

The deadline was originally December 2025 and was pushed back to 31 January 2027. In 2026 it was reported that it won't be delayed again, so it's sensible to treat that date as fixed.

You can already no longer buy copper lines

A "stop sell" is already in place. You can't order new copper phone lines, and you can't make most changes to existing ones, such as moving them to a new address. If you're planning an office move, this matters straight away.

Openreach has announced a temporary fallback called Emergency Voice Access for some home phone lines that haven't been moved in time. Don't rely on that for your business. Business premises still on copper by the deadline face having their lines disconnected.

What to check: it's not just phones

The phones on desks are the obvious bit. The things that catch businesses out are the other devices plugged into phone lines, often installed years ago and forgotten about. Check for:

• Burglar and fire alarms that call a monitoring centre
• Lift emergency phones
• Card payment terminals that dial out over a phone line
• Franking machines
• Fax machines
• Door entry and intercom systems
• Telecare and personal alarms, for example in care settings or for lone workers
• Building management or meter equipment that reports over a phone line

Some of these work fine on a digital line with an adapter. Others need replacing or moving to a mobile (SIM-based) connection. The supplier of each device can tell you which.

What to do now

1. List every line on your bill. Look at your phone bill for every number and line, including ones you don't recognise. Mystery lines are often alarms, lifts or old fax lines.
2. Match each line to what uses it. Walk round the building and follow the cables if you need to. Ask your alarm, lift and payment terminal suppliers what they need.
3. Talk to your provider now. Ask them which of your services are affected and what they'll move you to. Installers get busier as the deadline approaches.
4. Move your phones to a cloud phone system (VoIP). This replaces the old lines and usually the old phone system box in the cupboard too. See What is VoIP, and is it right for a small business?
5. Keep your numbers. Your existing numbers can almost always be moved across. See Can I keep my business phone number?
6. Sort your broadband at the same time. If your broadband rides on a phone line, it needs to move to SOGEA or full fibre. It may be a good moment to upgrade. See FTTC, FTTP or leased line?

Will it cost me more?

Not necessarily. Many businesses find that a cloud phone system and broadband without a phone line costs less than the old lines and phone system maintenance they were paying for. The costs to watch for are replacing equipment like alarm diallers or old payment terminals, so find those early.

Common questions

Will my phone number change?

No, not if you handle it properly. Numbers can be ported to a new digital service. The key thing is not to cancel your old lines before the move is complete.

What happens if I do nothing?

Your provider should contact you before your lines are switched over, but if a line still relies on the old network when it's withdrawn, it will stop working. That could mean phones, alarms or payment terminals going dead without warning.

Do I need new phones?

Sometimes. Some older desk phones can be connected through an adapter, but most businesses moving to VoIP take the chance to get new handsets or use apps on computers and mobiles instead.

Does this affect my mobile phones?

No. The switch-off is about landlines and the copper network. Mobile phones aren't affected.