PSTN Switch Off 2027: Why Your Business Mobile Is the Answer

Published: 23 February 2026 • Compare The Networks

The UK's Public Switched Telephone Network (PSTN) -- the copper-wire infrastructure that has carried landline calls since the 1800s -- is being permanently switched off by January 2027. For millions of UK businesses that still rely on a traditional landline, this is not a distant concern: it is happening now, and BT Openreach has already stopped selling new PSTN lines. If your business still depends on a landline, your mobile phone could be the most practical and cost-effective replacement.

What Is the PSTN Switch Off?

The PSTN (Public Switched Telephone Network) is the analogue and ISDN network that underpins traditional UK landlines. BT Openreach, which owns and maintains this infrastructure, has confirmed that all PSTN services will be withdrawn by January 2027.

This means:

• All traditional analogue landlines will stop working
• ISDN lines (ISDN2 and ISDN30) will be permanently disconnected
• Any equipment connected via a standard phone socket (fax machines, alarm systems, payment terminals) will need replacing or adapting
• Businesses must move to an IP-based (internet-based) alternative

The Timeline: Where Are We Now?

Tip If you still have a traditional landline, your provider should have contacted you about migration. If you have not heard anything, contact them now -- do not wait until the final switch-off date.

Why a Business Mobile Is the Best Replacement

While the official BT narrative pushes Digital Voice (their VoIP-over-broadband service), many businesses are finding that a business mobile -- combined with a virtual landline number -- is a superior alternative. Here is why:

1. No Dependency on Broadband

IP-based landline replacements like Digital Voice require a working broadband connection. If your internet goes down, so does your phone. A mobile phone works on the 4G/5G network independently, giving you a completely separate communication channel.

2. Virtual Landline Numbers

One common concern is losing a recognisable local or 01/02 number. With a virtual landline service, you can keep your existing geographic number and have calls forwarded directly to your mobile. Customers call your familiar landline number; you answer on your mobile. They never know the difference.

3. Dual SIM and eSIM Capability

Modern smartphones support eSIM technology, allowing you to run two numbers on one device -- your mobile number and a virtual landline number. This means you can separate business and personal calls on a single handset without carrying two phones.

4. Total Portability

Unlike a VoIP desk phone tied to your office broadband, a mobile goes wherever you do. For businesses with field workers, remote staff, or directors who travel, this is a fundamental advantage.

5. Lower Ongoing Costs

A traditional BT business landline typically costs £25-£35 per month for line rental alone, with call charges on top. A business mobile SIM with unlimited calls and generous data starts from around £10-£15 per month. Add a virtual landline number at £5-£8 per month, and you are still paying less than the old landline cost.

Cost Comparison: Landline vs Mobile-Based Solution

A saving of £300 per year per line adds up quickly. A business with three landlines switching to mobile-based solutions could save £900 annually.

How to Replace Your Landline with a Business Mobile

Making the switch is simpler than you might think. Follow these steps:

Step 1: Audit Your Current Setup

• How many landlines do you have?
• Do you have any equipment connected (fax, alarm, EPOS)? These need separate solutions.
• Is your broadband delivered over the same line? If so, ensure your broadband will continue after PSTN shutdown (most fibre/FTTC broadband is unaffected).
• Do customers know and use your landline number?

Step 2: Port or Redirect Your Landline Number

If customers know your 01/02 number, you will want to keep it. You have two options:

1. Port the number to a virtual landline provider -- this transfers ownership of the number, so calls route directly to your mobile or VoIP app
2. Set up a permanent redirect -- your current provider can redirect all calls to your mobile number. This is simpler but you remain tied to the old provider.

Step 3: Choose a Business Mobile Plan

Select a business SIM-only deal with unlimited calls and enough data for your needs. For most small businesses, a plan with 50-100GB of data and unlimited UK calls will be more than sufficient.

Step 4: Set Up a Virtual Landline Number

A virtual landline service gives you a local or national number that forwards to your mobile. Features typically include:

• Call forwarding to any UK mobile or multiple mobiles
• Voicemail with email transcription
• Business hours routing (send calls to voicemail outside working hours)
• Call recording
• Auto-attendant ("Press 1 for sales, 2 for support...")

Step 5: Consider VoIP Apps for Advanced Features

If you need more than basic call forwarding -- such as conference calling, call queues, or integration with your CRM -- consider a business VoIP app on your mobile. Services like Microsoft Teams Phone, 3CX, and RingCentral run on your smartphone and provide full business phone system features without any desk hardware.

What About Alarm Systems and Payment Terminals?

Landlines are not just used for voice calls. Many businesses have equipment connected via the PSTN:

• Burglar alarms -- older alarm systems use the phone line to call the monitoring centre. You will need a GSM communicator (a mobile module) fitted to your alarm panel, or upgrade to an IP-based alarm system.
• Card payment terminals -- dial-up terminals that connect via the phone line must be replaced with 4G or WiFi-enabled card machines. See our card terminal comparison for options.
• Fax machines -- online fax services (fax-to-email) replace physical fax machines entirely and cost a fraction of the old setup.
• Door entry systems -- intercom systems that dial a landline number can be reconfigured to call a mobile number instead.

The Risks of Doing Nothing

If you take no action before January 2027:

• Your landline will stop working entirely -- no incoming or outgoing calls
• Any equipment connected to the line will fail
• If customers call your old landline number, they will hear a dead line or disconnection message
• You will have no time to plan a smooth transition -- rushed migrations are more likely to cause disruption

The bottom line: acting now gives you control over the process and the opportunity to save money by choosing the best replacement solution.