Business Telephone Line UK 2026: Types, Costs & How the Switchover Affects You

Your business telephone line is the backbone of how your company communicates — with customers, suppliers, and partners. Yet with the PSTN switch-off looming in January 2027, thousands of UK businesses face a critical decision: stick with legacy infrastructure until the very last moment, or make a strategic move to modern telephony now.

In this comprehensive guide, we break down everything you need to know about business telephone lines in the UK in 2026 — from the different types available and their costs, to number porting, virtual numbers, and how to future-proof your communications before the switchover deadline. Whether you’re a sole trader needing a single line or a multi-site enterprise requiring hundreds, this guide has you covered.

What Is a Business Telephone Line?

A business telephone line is a dedicated telephony connection used by a company to make and receive calls. Unlike residential lines, business lines typically offer enhanced features such as call queuing, auto-attendant menus, hunt groups, and service-level agreements (SLAs) that guarantee uptime and rapid fault resolution.

Historically, business telephone lines in the UK were delivered over the Public Switched Telephone Network (PSTN) or ISDN (Integrated Services Digital Network). Today, the market has shifted dramatically towards Voice over Internet Protocol (VoIP) and SIP trunking, driven by lower costs, greater flexibility, and the impending retirement of the copper network.

Types of Business Telephone Line in the UK

Understanding the different types of business telephone line available is essential for making an informed decision. Here’s a breakdown of the main options in 2026:

Traditional Analogue Landline (PSTN)

The traditional analogue line has served UK businesses for decades. It uses copper wiring to connect your premises to the local exchange, delivering a single voice channel per line. While reliable, PSTN lines are now in their twilight years. Openreach has confirmed that all PSTN and ISDN services will be switched off by January 2027, meaning no new connections are available in many exchange areas, and existing lines will cease to function after the cut-off date.

ISDN Lines (ISDN2 and ISDN30)

ISDN was the step up from analogue, offering digital voice channels with better call quality and the ability to carry multiple simultaneous calls. ISDN2 provides two channels per connection, while ISDN30 delivers up to 30 channels — making it the workhorse for larger offices and call centres. Like PSTN, ISDN is being retired in 2027 and is no longer available as a new installation in most areas.

VoIP Business Telephone Lines

VoIP delivers voice calls over your internet connection rather than traditional copper lines. It’s now the default choice for new business telephone line installations in the UK. VoIP lines offer a vast array of features — from call recording and voicemail-to-email to integration with CRM systems — at a fraction of the cost of legacy alternatives. For a deeper dive, see our complete business phone line guide.

SIP Trunking

If your business already has an on-premises PBX system, SIP trunking allows you to connect it to the telephone network via your broadband connection. This effectively replaces your ISDN lines without requiring you to scrap your existing phone system. It’s a cost-effective bridge for businesses that want modern connectivity without a full hardware overhaul.

Hosted (Cloud) Phone Systems

Hosted telephony takes VoIP a step further by moving your entire phone system to the cloud. There’s no on-site PBX to maintain — everything is managed through an online portal. This is ideal for businesses with remote or hybrid workforces, multi-site operations, or those wanting to eliminate capital expenditure on hardware.

Business Telephone Line Costs: 2026 Comparison

Cost is often the deciding factor when choosing a business telephone line. Below is a comparison of typical monthly costs across the main line types available in 2026:

As the table illustrates, VoIP and SIP-based business telephone lines are significantly cheaper than their legacy equivalents — often delivering savings of 40–60% on monthly telephony costs. When you factor in the inclusive call bundles that most VoIP providers offer, the savings become even more pronounced.

The PSTN Switch-Off 2027: How It Affects Your Business Telephone Line

The single biggest event impacting UK business telephony is the PSTN and ISDN switch-off, scheduled for January 2027. Openreach is retiring the entire copper-based telephone network, meaning every analogue and ISDN business telephone line in the country will stop working.

This isn’t a distant threat — it’s happening now. Openreach has already designated hundreds of exchanges as “stop sell” areas, where no new PSTN or ISDN lines can be ordered. If your business still relies on traditional lines, you need to act promptly to avoid disruption.

What You Need to Do

1. Audit your current lines — Identify every PSTN and ISDN connection across your sites, including those used for alarm systems, fax machines, and card payment terminals.
2. Assess your broadband — VoIP requires a stable internet connection. Ensure your broadband can handle voice traffic alongside your existing data usage.
3. Choose a replacement solution — Whether that’s VoIP lines, SIP trunks, or a full hosted phone system, select the option that fits your business needs and budget.
4. Port your numbers — Keep your existing business telephone numbers (more on this below).
5. Plan the migration — Work with an experienced provider like Connection Technologies to ensure a seamless transition with zero downtime.

How to Get a New Business Telephone Line

Setting up a new business telephone line in 2026 is straightforward, especially if you opt for VoIP or hosted telephony. Here’s the typical process:

Step 1: Determine Your Requirements

How many simultaneous calls do you need to handle? Do you need features like call recording, IVR menus, or CRM integration? Will staff be working remotely? Answering these questions helps you size the solution correctly.

Step 2: Check Your Broadband

Each VoIP call uses approximately 100 kbps of bandwidth. A standard fibre broadband connection can comfortably handle 20+ simultaneous VoIP calls. For larger deployments, a dedicated leased line may be advisable.

Step 3: Choose Your Provider

Look for a provider that offers UK-based support, flexible contracts, transparent pricing, and a proven track record with businesses similar to yours. Connection Technologies ticks all these boxes, providing bespoke business telephone line solutions backed by dedicated account management.

Step 4: Select Your Numbers

You can port your existing numbers (see below), choose new local or national numbers, or add virtual numbers for geographic presence in other regions.

Step 5: Installation and Go-Live

With VoIP, there’s often no physical installation required. Handsets can be pre-configured and shipped to your premises, or staff can use softphone apps on their computers and mobiles. Most businesses are up and running within a few working days.

Number Porting: Keep Your Existing Business Telephone Number

One of the most common concerns when switching provider or technology is losing your established business telephone number. The good news is that number porting allows you to transfer your existing numbers to a new provider or platform, so your customers never notice the change.

The porting process in the UK typically takes 7–10 working days for standard geographic numbers, though complex multi-number ports may take slightly longer. A reputable provider will manage the entire process for you, coordinating with your existing supplier to ensure continuity.

At Connection Technologies, we handle number porting as a standard part of every business telephone line migration — ensuring your numbers transfer smoothly with no interruption to service.

Virtual Business Telephone Numbers

Virtual numbers are a powerful tool for UK businesses. They allow you to present local telephone numbers in cities or regions where you don’t have a physical office, giving the impression of local presence and increasing customer trust.

For example, a Manchester-based company could hold virtual numbers with London (020), Birmingham (0121), and Edinburgh (0131) dialling codes — all routing to the same team. You can also add non-geographic numbers such as 0800 (freephone) or 0333 (national rate) for marketing campaigns.

Virtual numbers work seamlessly with VoIP and hosted phone systems, making them easy to set up and manage through an online portal.

Choosing a Business Telephone Line Provider: What to Look For

The UK market is crowded with telephony providers, so it pays to be selective. Here are the key criteria to evaluate:

• UK-based support — When you have an issue, you need to speak to someone who understands UK telecoms infrastructure and can resolve problems quickly.
• Flexible contracts — Avoid being locked into lengthy agreements that don’t allow you to scale up or down as your business evolves.
• Transparent pricing — Watch out for hidden setup fees, per-minute call charges, or premium-rate support lines.
• Feature set — Ensure the platform includes the features you need: call recording, voicemail-to-email, auto-attendant, call analytics, mobile apps, and integrations.
• Reliability and SLAs — Look for guaranteed uptime (99.9%+) and clearly defined response times for fault resolution.
• Migration support — The best providers manage the entire switchover process, including number porting, hardware configuration, and staff training.

Connection Technologies consistently delivers on all of these criteria, which is why we’re trusted by businesses across the UK — from SMEs to large enterprises — to deliver reliable, cost-effective business telephone line solutions.

Why 2026 Is the Year to Act

With the PSTN switch-off less than a year away, businesses that delay risk a rushed migration — or worse, losing service entirely. Moving to a VoIP-based business telephone line now gives you time to:

• Test the new system thoroughly before the deadline
• Train staff on new features and workflows
• Optimise your broadband and network infrastructure
• Take advantage of cost savings immediately, rather than paying premium rates on legacy lines until the last minute

The businesses that act early gain a competitive advantage — better call quality, lower costs, greater flexibility, and the confidence that their communications are future-proofed for years to come.