What is a VoIP Phone Number? UK Business Guide (2026 Update)

With BT's PSTN network switching off in 2027, thousands of UK businesses are asking the same question: what exactly is a VoIP phone number, and how does it replace my landline?

A VoIP phone number is a telephone number that routes calls over the internet instead of traditional copper phone lines. Unlike landlines tied to physical locations, VoIP numbers exist in the cloud and can be used on any internet-connected device—your mobile, laptop, or desk phone—anywhere in the world.

This guide explains everything UK businesses need to know about VoIP phone numbers, from how they work and what types are available, to costs, security, and the practical steps to make the switch before the 2027 deadline.

Quick Answer: What is a VoIP Phone Number?

A VoIP (Voice over Internet Protocol) phone number is a virtual telephone number that makes and receives calls using internet connectivity rather than traditional phone lines. The number is assigned to a user or team, not a physical phone socket, allowing the same number to ring simultaneously on desk phones, mobiles, and computers. VoIP numbers look identical to traditional UK numbers but operate through cloud-based systems.

VoIP Number vs VoIP Service vs VoIP Phone System

It's easy to confuse these terms:

• VoIP number: The actual telephone number (like 020 7946 0958) that callers dial to reach you.
• VoIP service: The underlying technology and provider infrastructure that delivers calls over the internet.
• VoIP phone system: The complete business solution including numbers, call management features, phones or apps, and admin controls—often called a cloud PBX or hosted phone system.

Think of it this way: the VoIP number is your digital address, the service is the postal system, and the phone system is the entire office communication infrastructure.

How VoIP Phone Numbers Work

Internet Telephony Basics (The Simple Version)

When someone calls your VoIP number, here's what happens:

1. The caller dials your number from any phone.
2. Their call reaches your VoIP provider's servers through the internet.
3. Your provider's system identifies where you want calls sent—your office phone, mobile app, or multiple devices at once.
4. The call connects through the internet as digital data packets.
5. You answer on whichever device you're using.

The magic is that your business number isn't tied to a wall socket anymore. Your 020 London number works perfectly when you're working from a café in Edinburgh or your home office.

Behind the Scenes: The Technical View

For those interested in how the technology actually works:

• VoIP converts your voice into digital packets using codecs (compression algorithms).
• These packets are transmitted over IP networks using protocols like SIP (Session Initiation Protocol) for call setup and RTP (Real-time Transport Protocol) for the actual voice stream.
• Quality of Service mechanisms prioritise voice packets to maintain call quality.
• At the receiving end, packets are reassembled and converted back to audio.

Modern VoIP systems use advanced codecs like Opus and G.722 to deliver HD voice quality that often exceeds traditional phone call clarity.

Devices & Apps: Use Your Number Anywhere

VoIP numbers work on:

• Desk phones: IP phones that look like traditional office phones but connect via ethernet rather than phone lines. Popular brands include Yealink, Poly, and Cisco.
• Softphones: Desktop or mobile apps that turn your computer or smartphone into a business phone. Most UK VoIP providers offer branded apps for iOS, Android, Windows, and Mac.
• Web browsers: Many systems now support WebRTC, allowing you to make calls directly from Chrome, Firefox, or Safari without installing software.
• Existing phones: Through VoIP adapters (ATAs), you can connect traditional analogue phones to VoIP systems, useful during migration periods.

The same number rings on all your chosen devices simultaneously. Answer on your mobile during your commute, transfer to your desk phone when you arrive, and take your laptop home for evening calls—all using one business number.

Types of VoIP Numbers Available in the UK

UK VoIP numbers follow Ofcom's National Numbering Plan, giving businesses multiple options depending on their needs.

Local Geographic Numbers (01 and 02)

These are area-code numbers that give your business a local presence:

• 02 numbers: Major cities including 020 (London), 028 (Northern Ireland), 029 (Cardiff)
• 01 numbers: Everywhere else—0161 (Manchester), 0131 (Edinburgh), 01603 (Norwich), and hundreds more

Best for: Businesses wanting to appear local to customers in specific regions, even if your team works remotely nationwide.

Costs to callers: Included in most mobile and landline call packages, or standard geographic rates apply.

Migration note: You can port your existing 01 or 02 landline numbers to VoIP, maintaining customer recognition and avoiding the need to update marketing materials.

National Non-Geographic Numbers (03, 084, 087)

These numbers aren't tied to geographic locations:

• 03 numbers (0330, 0333, 0345): Charged at the same rate as 01/02 numbers, included in caller packages. Ideal for businesses serving customers UK-wide without favouring one region.
• 084 and 087 numbers: Revenue-sharing numbers where the business receives a portion of call charges. Less common now due to consumer preference for inclusive-minute numbers.
• 056 numbers: Ofcom reserved this range specifically for VoIP services, though many providers still use traditional geographic ranges.

Best for: National businesses, charities, government services, or any organisation wanting a unified UK presence.

Toll-Free Numbers (0800 and 0808)

Free for callers, paid by your business:

These are essential for customer service lines, support helpdesks, and sales teams where you want to remove cost barriers for callers. Since 2015, 0800 numbers have been free from UK mobiles as well as landlines.

Costs: Your business pays per-minute charges for received calls (typically 3p–8p per minute) plus a monthly number rental fee.

Marketing benefit: Toll-free numbers increase response rates in advertising because callers know they won't be charged.

Mobile VoIP Numbers (07)

Some VoIP providers offer 07 mobile-style numbers that work like any other VoIP number but look like mobile numbers to callers:

Use cases: Freelancers and sole traders who want the flexibility of VoIP but prefer the professional informality of a mobile number. Estate agents, consultants, and field service workers often choose these.

Limitation: Not all UK VoIP providers offer 07 numbers due to Ofcom allocation restrictions.

International Virtual Numbers

VoIP providers can issue numbers from other countries that ring through to your UK-based team:

A London startup can offer a New York number (+1 212) for US customers, a Paris number (+33 1) for French clients, and a Sydney number (+61 2) for Australian contacts—all routing to the same UK office without international offices or phone systems.

Available countries: Most major markets, including USA, Canada, Australia, France, Germany, Spain, Italy, and dozens more.

Best for: Businesses expanding internationally, e-commerce companies supporting overseas customers, or UK companies with expat customer bases.

VoIP Number vs Landline & Mobile: Key Differences

Understanding how VoIP numbers compare to traditional options helps explain why UK businesses are switching before they're forced to.

The Impact of the 2025/2027 ISDN Switch-off

BT and Openreach stopped selling new PSTN and ISDN lines in September 2023. The network completely shuts down in January 2027, after which traditional landlines simply won't work.

For UK businesses, this means:

• 2025–2026: Transition period. Existing landlines still function but providers are actively migrating customers to VoIP alternatives.
• January 2027: Full stop. The PSTN network powers down. Any remaining landline-dependent services (door entry systems, alarms, payment terminals, lift phones) stop working unless migrated.

Action required: Every UK business with landlines must either switch to VoIP or find alternative communication methods. Number porting to VoIP is the most common solution, maintaining continuity for customers.

Ofcom has published detailed guidance on the migration, requiring providers to ensure vulnerable customers aren't left without service and that emergency calling remains available.

Portability: Why VoIP Numbers Are Easier to Move

One of VoIP's biggest practical advantages is true number portability:

• Change providers without changing numbers: Unhappy with your VoIP provider? Port your numbers to a competitor in 5–10 business days without telling customers.
• Relocate offices seamlessly: Moving from Manchester to Bristol? Your 0161 Manchester number moves with you, maintaining customer recognition.
• Flexible working: Staff working from home, abroad, or travelling can use the main business number without complicated call forwarding.
• Business continuity: If your office floods, burns, or loses power, divert all numbers to mobile phones or staff working from home in minutes, not days.

Traditional landlines require physical infrastructure changes and often mean new numbers when you move premises—confusing for customers and expensive for marketing updates.

Top Benefits of VoIP Numbers for Business

Beyond replacing dying landline technology, VoIP numbers deliver operational advantages traditional phones never could.

Cost Efficiency: Stop Paying for Phone Lines

Most UK businesses save 40–60% on phone costs by switching to VoIP:

• No line rental: Traditional landlines charge £15–£25 per line monthly before you make a single call. VoIP systems charge per user (typically £8–£15), with calls often included.
• Unlimited UK calling: Many VoIP packages include unlimited calls to UK landlines and mobiles, eliminating per-minute charges.
• Cheaper international calls: Rates to USA, Europe, and other countries are typically 60–80% lower than BT landline rates.
• Reduced hardware costs: No expensive PBX boxes to buy (costing thousands) or maintain (hundreds annually). VoIP systems are hosted in the cloud with monthly subscriptions.
• Single network: Combine voice and data on one internet connection instead of paying separately for phone lines and broadband.

A 10-person business paying £350 monthly for landlines plus call charges typically reduces phone costs to £120–£180 monthly with VoIP, saving over £2,000 annually.

Remote & Hybrid Work Enablement

VoIP numbers made work-from-home viable during COVID lockdowns and continue supporting flexible working:

• Employees use the business number on personal mobiles or home computers without giving out private numbers.
• Customers can't tell if you're answering from the office, home, or a beach in Spain.
• Call quality remains consistent across locations.
• Managers can see real-time presence (available, on a call, away) regardless of where team members are working.

For hybrid teams splitting time between office and home, VoIP means phones work identically in both locations—no special forwarding setups or complicated transfer processes.

Scalability: Grow Without Infrastructure Projects

Adding capacity to traditional phone systems meant engineer visits, new physical lines installed, and hardware purchases. VoIP scales instantly:

• Add users in minutes: Log into your admin portal, create a user, and assign a number. New staff can start taking calls within an hour.
• Seasonal scaling: Call centres handling Christmas volume can add 50 temporary staff for 6 weeks without permanent infrastructure changes.
• No physical limitations: Traditional systems maxed out at line capacity (the PBX could only handle X simultaneous calls). Cloud VoIP scales automatically to demand.
• Multi-site made simple: Opening a second office? No new phone system needed—just add users and numbers to your existing account.

This flexibility particularly benefits growing businesses that previously had to over-invest in capacity to allow for future growth.

Privacy & Work-Life Balance

Before mobile VoIP apps, remote workers faced an uncomfortable choice: give customers your personal mobile number, or have complex call forwarding eat your mobile minutes.

VoIP numbers solve this:

• Staff make and receive business calls on personal devices using the VoIP app.
• Personal mobile numbers stay private—customers only see the business number.
• When you leave the company, log out of the app. Your personal number was never exposed.
• Outside working hours, turn off the app. Business calls go to voicemail or colleagues without your personal phone ringing.

Sales teams, support staff, and managers particularly value this professional boundary between work and personal life.

Advanced Business Features Included

Features that cost hundreds extra on traditional PBX systems are standard in modern VoIP:

• Call recording: Automatically record calls for training, quality, or compliance. Search and playback recordings from a web dashboard.
• Call analytics: See who's calling, when, call durations, missed calls, and busiest periods. Identify trends and optimise staffing.
• Auto-attendant (IVR): "Press 1 for sales, 2 for support" menus that route calls intelligently without a receptionist.
• Call queuing: During busy periods, customers hear hold music and their position in the queue rather than hearing engaged tones.
• Voicemail to email: Missed calls deliver voicemail recordings to your inbox as audio files, with transcriptions.
• CRM integration: Calls automatically log in systems like Salesforce, HubSpot, or Microsoft Dynamics. Customer records pop up automatically when they call.
• Presence and chat: See which colleagues are available and send instant messages alongside voice calling—unified communications.
• Call whisper and barge: Managers can listen to calls, whisper coaching to staff without customers hearing, or join calls to help.

These features transform phones from simple call devices into powerful business intelligence and customer service tools.

How to Get a VoIP Number: Step-by-Step

Setting up VoIP numbers is simpler than most UK businesses expect. Here's the realistic process:

Step 1: Choose a VoIP Provider and Plan

Research UK VoIP providers comparing:

• Reliability and uptime: Look for 99.9%+ uptime SLAs backed by service credits if they fail to meet it.
• UK-specific features: 999 emergency calling with address registration, local UK numbers, and UK-based support.
• Pricing structure: Per-user licensing vs pay-as-you-go. Included minutes vs extra charges. Contract length and exit terms.
• Feature set: Which features you actually need vs marketing fluff. Don't pay for call centre features if you're a 5-person consultancy.
• Integration support: Does it connect with your CRM, helpdesk, or accounting software?
• Reviews and reputation: Check Trustpilot, Google reviews, and ask for customer references. How do they handle support queries and outages?

Most providers offer free trials—test call quality, app usability, and admin portal ease before committing.

Step 2: Select Number Type and Area Code

Decide which numbers your business needs:

• Geographic presence: Want a London 020 number to appear established in the capital? A Birmingham 0121 number for Midlands customers?
• National reach: Prefer a non-geographic 0330 number showing you serve all of UK?
• Toll-free for customer service: Essential for support lines but adds per-minute costs.
• Multiple numbers: Many businesses use different numbers for sales, support, and accounts—routing to appropriate teams.
• International numbers: If you have overseas customers, local numbers in their countries dramatically improve answer rates.

Some providers include one number free; others charge £2–£5 monthly per additional number.

Step 3: Buy New vs Port Existing Numbers

• New numbers: Instant. Choose from available numbers and start using them immediately—usually within minutes to hours.
• Porting existing numbers: Transferring your current landline or VoIP numbers to the new provider:
  • The process takes 5–10 working days on average.
  • You'll need your current provider's account details and authorisation codes.
  • Your old provider cannot refuse porting, but they may attempt retention offers.
  • During porting, there's typically no service interruption—old and new systems run in parallel briefly, then the cutover happens.

Critical: Don't cancel your old service before porting completes. This releases the numbers back to the pool, making them unrecoverable.

For businesses switching before the PSTN shutdown, porting maintains customer continuity—your existing marketing materials, website, and business cards remain accurate.

Step 4: Configure Devices and Apps

Set up how your team will actually use the numbers:

• Download apps: Install your provider's softphone on smartphones (iOS/Android) and computers (Windows/Mac/Linux). Log in with the provided credentials.
• Configure desk phones: If using IP phones, they're usually plug-and-play. Connect to your network via ethernet, enter SIP credentials, and they register automatically.
• Set up call routing: In the admin portal, configure where calls go—ring all devices simultaneously, route to specific people or teams, set up out-of-hours forwarding.
• Voicemail greetings: Record professional messages for individual users and the main company line.
• Emergency address: UK regulations require you to register the physical address where each user will primarily use the service for 999/112 calling accuracy.

Most providers offer onboarding support—some even configure devices remotely or send pre-configured phones.

Step 5: Test, Train, and Roll Out

Before going live:

• Test call quality: Make test calls between team members and from external numbers. Check audio clarity, latency, and app reliability.
• Verify routing: Ensure calls reach the right people and teams. Test voicemail, hold music, and auto-attendant menus.
• Emergency call test: Verify 999/112 calling works and sends the correct location to emergency services.
• Staff training: Show team members how to use the apps—making calls, transferring, checking voicemail, updating status. This takes 15–30 minutes for most users.
• Parallel running: If porting numbers, run both old and new systems briefly to ensure nothing's missed during transition.
• Inform customers: If changing main numbers, give customers adequate notice through email, website updates, and phone messages on old numbers.
• Monitor and adjust: Watch call patterns in the first weeks. Adjust routing, staffing, and features based on real usage.

Pricing & Costs for UK VoIP Numbers

VoIP pricing seems complex at first, but breaks down into predictable components.

Number Rental and User Licensing

• Number rental: £0–£5 per number monthly. First number often included free; additional numbers charged separately. Toll-free numbers typically cost more (£5–£8 monthly).
• User licenses: £8–£25 per user monthly, depending on feature tier.
  • Basic packages (£8–£12) include calling and core features.
  • Advanced packages (£15–£25) add call recording, analytics, and integrations.
• Concurrent call limits: Some providers charge based on simultaneous calls rather than named users. This suits businesses where not everyone is on calls at once.

Included Minutes and Call Rates

Unlimited UK calls: Most business packages include unlimited calls to UK landlines and mobiles. Verify this specifically—some budget providers still charge per minute.

International calls: Typically pay-as-you-go. Rates vary dramatically by destination:

• USA/Canada: 1–2p per minute
• Western Europe: 2–5p per minute
• Mobile phones internationally: 5–15p per minute
• Emerging markets: 10–50p+ per minute

Receiving calls: Inbound calls are generally free on geographic numbers but cost 3–8p per minute on toll-free numbers.

Typical Cost Scenarios for UK Businesses

• Micro business (1–3 users):
  • User licenses: £25–£40 monthly
  • Number rental: £0–£10 monthly
  • Calls: Included
  • Total: £25–£50 monthly
• Small business (10 users):
  • User licenses: £80–£150 monthly
  • Additional numbers: £10–£20 monthly
  • Calls: Included (UK)
  • Total: £90–£170 monthly
• Medium business (50 users, call centre features):
  • User licenses: £500–£800 monthly
  • Multiple numbers and toll-free: £50–£80 monthly
  • Toll-free inbound minutes: £100–£300 monthly
  • Total: £650–£1,180 monthly

Compare this to equivalent traditional phone systems costing 50–100% more, plus capital expenditure for PBX hardware.

Cost Gotchas to Watch For

• Premium rate forwarding: Forwarding toll-free numbers to mobile phones can incur double charges—you pay to receive the toll-free call, then pay again to forward it to a mobile.
• International destination charges: Calls to international mobiles often cost 5–10× more than landlines in the same country.
• Unused features: Paying for advanced packages when you only use basic calling wastes money. Most businesses start with mid-tier plans and upgrade if needed.
• Lock-in contracts: Some providers offer cheap rates with 24–36 month contracts and expensive early exit fees. Month-to-month or 12-month contracts offer better flexibility.
• Hidden setup fees: One-time charges for number porting (£5–£25 per number), account setup (£50–£200), or device configuration.
• Out-of-bundle usage: If you exceed included minutes (rare with unlimited UK packages), per-minute charges apply—review your first few bills to spot this.
• Toll-free abuse: If you publish toll-free numbers publicly, spam callers or bots can run up your inbound minute charges. Providers offer spam filtering, but it's not perfect.

Security, Compliance & Emergency Calling

VoIP numbers are safe and reliable when set up properly, but they do introduce considerations traditional landlines didn't have.

Is a VoIP Number Secure? Encryption and Fraud

• Call encryption: Reputable VoIP providers encrypt calls using SRTP (Secure Real-time Transport Protocol) and TLS (Transport Layer Security). This means calls are harder to intercept than traditional phone calls, which travel unencrypted over copper wires.
• Account security: Use strong passwords and enable two-factor authentication on admin portals. Weak security can lead to toll fraud—hackers make expensive international calls on your account.
• Fraud protection: Modern VoIP systems include fraud detection that flags unusual calling patterns (e.g., sudden calls to premium-rate international destinations). Set spending limits and geographic restrictions.
• Number spoofing: Scammers can make calls appear to come from any number, including yours. This is a problem across all phone systems, not unique to VoIP. You can't stop spoofers using your number, but authentic caller ID services help recipients verify real calls.
• Data protection: If you record calls, you must comply with UK GDPR and inform callers. Most VoIP systems include compliant warning announcements.

Emergency Calling: 999 and 112 on VoIP

VoIP handles emergency calls differently than landlines, requiring specific setup:

• Location registration: You must register the physical address where each user will primarily use the service. When they dial 999/112, this address goes to emergency services. If staff work from multiple locations, update addresses accordingly.
• Mobile workers: Emergency services receive the registered address, not where the caller actually is. Staff should verbally confirm their location when calling emergency services.
• Power and internet dependency: Traditional landlines work during power cuts because telephone exchanges provide power through the copper wires. VoIP needs a working internet and power. For critical safety systems (alarms, lifts, care facilities), install battery backup (UPS) and 4G failover internet.
• Ofcom requirements: Providers must clearly explain emergency calling limitations before you sign up and during onboarding.
• Testing: Verify 999 calling works during setup. Ofcom offers a test number (0800 83 222 22) that mimics emergency services without dispatching real responders.

For most businesses, these limitations are minor. Critical infrastructure facilities (hospitals, care homes) may need traditional phone line backup until IP-based emergency services fully mature.

Internet and Power Dependency: Backup Plans

VoIP reliability depends on your internet connection and electricity:

Internet quality: Poor broadband causes dropped calls, robotic audio, and delays. You need:

• Upload speed: Minimum 100 kbps per concurrent call
• Latency: Under 150ms for good quality
• Jitter: Low and consistent
• Packet loss: Under 1%

Most UK fibre broadband easily meets these requirements. Quality of Service (QoS) router settings prioritise voice traffic over other data.

Backup internet: For businesses where phones are critical, consider:

• 4G/5G failover routers that switch to mobile data if broadband fails
• Secondary internet connection from a different provider/technology
• Staff using VoIP apps on 4G when the office internet is down

Power backup: Uninterruptible Power Supply (UPS) units keep routers, switches, and desk phones running during outages. Battery systems for 2–4 hours cost £100–£500 depending on capacity.

Disaster recovery: VoIP's flexibility is a backup advantage—office floods? Instantly divert all calls to staff mobiles and work from home until repairs are complete.

Common Business Use Cases

VoIP numbers solve specific business problems across different scenarios.

Small Business Multi-Line Setup

A 5-person consultancy previously had 2 landlines (£50 monthly) with limited features. With VoIP:

• Each consultant gets their own direct number, but calls can overflow to colleagues.
• Clients call the main number and the automated menu routes them to the right person.
• When working from home, the office number works perfectly on mobile apps.
• Call recording captures client instructions without manual note-taking.
• Voicemail messages arrive in email, so they're never missed.

Cost reduced by 40%, functionality increased dramatically.

Call Centres and Customer Support Teams

Support teams need features traditional systems couldn't provide affordably:

• Call queuing: Customers hear their position in the queue and the estimated wait time rather than engaged tones.
• Skills-based routing: Technical queries route to tech specialists; billing questions to the accounts team.
• Call recording and analytics: Every call is recorded automatically for training and quality monitoring. Analytics show average handle time, busiest periods, and missed calls.
• Softphone flexibility: Agents work from anywhere with internet. Hire nationwide rather than limiting to office-commutable candidates.
• CRM integration: Customer records pop automatically when they call, showing previous interactions and account status.
• Real-time monitoring: Supervisors see live dashboards of who's on calls, queue lengths, and service level compliance.

Teams of 10–50 agents can implement professional contact centre functionality for a fraction of traditional costs.

Marketing Campaign Tracking

Businesses running multiple advertising campaigns use unique VoIP numbers to track effectiveness:

A property agency runs ads in 5 different newspapers, each listing a different phone number (all routing to the same sales team). Call analytics show which publication generates the most leads. ROI calculation becomes precise—spend £500 on The Times ad, got 12 calls, closed 2 sales worth £20,000 total.

Digital marketers use dynamic number insertion—website visitors from Google Ads see one number, visitors from Facebook see another, allowing channel-specific conversion tracking.

International Business: Virtual Local Presence

A UK e-commerce business selling to US customers issues a toll-free US number (+1 800) that rings the Manchester office:

• American customers call free local numbers, not expensive international ones.
• Answer rates increase 3–4× because customers trust familiar local numbers.
• The business appears established in the US market without physical offices or staff there.
• As business grows in Australia and Germany, add virtual numbers in those markets too.

This strategy dramatically lowers barriers to international expansion.

Hybrid and Remote Teams

The pandemic proved VoIP essential for distributed workforces:

Team members in Glasgow, Bristol, and London all answer the main London office number. Customers can't tell who's where—service continuity is seamless. Conference calls use built-in meeting features rather than expensive third-party services. Presence indicators show who's available for internal calls. Hot-desking becomes simple—log into any desk phone with your credentials, or just use the app.

Companies have closed expensive city-centre offices, moved to smaller flexible spaces, and maintained professional phone presence through VoIP.

UK Regulation and the PSTN Transition

Understanding the regulatory landscape helps UK businesses plan their VoIP migration.

Ofcom Numbering Policies

Ofcom, the UK communications regulator, controls how phone numbers are allocated and used:

• Geographic numbers (01/02): Allocated by area code. VoIP providers must demonstrate they serve customers in that area, preventing abuse. Businesses can hold geographic numbers for locations where they have presence or customers.
• Non-geographic numbers: Allocated nationally without location restrictions. The 056 range is specifically designated for VoIP services, though providers also use traditional ranges.
• Number porting: Ofcom guarantees your right to port numbers between providers. Losing providers cannot unreasonably block ports and must complete transfers within specified timeframes.
• Call charge transparency: Regulations require clear disclosure of call costs. Non-geographic numbers must display per-minute charges and any access charges.
• Caller ID authentication: Ofcom is implementing measures to combat number spoofing and scam calls, requiring providers to verify caller identity for outbound calls.
• Emergency calling standards: Providers offering 999/112 calling must meet accuracy and reliability standards, including correct location information.

BT and Openreach PSTN/ISDN Sunset

The traditional phone network is shutting down on a published timeline:

• September 2023: Stop-sell. BT and Openreach stopped accepting orders for new PSTN and ISDN lines. Existing lines remain active, but new installations are impossible.
• 2025–2026: Active migration. Providers are contacting customers and moving them to VoIP equivalents. Many businesses are being migrated automatically unless they opt for different providers.
• January 2027: Switch-off. The PSTN network powers down completely. Any remaining landline-dependent devices and services stop working.

Impact on businesses:

• 2.7 million UK businesses still using landlines must migrate
• Services depending on landlines (alarms, door entry, payment terminals, lift phones) need upgrading or replacement
• Older fax machines may need VoIP-compatible replacements or cloud fax services

Ofcom requires providers to ensure vulnerable customers (elderly, those with health conditions requiring phone-based medical alerts) are not left without service during the transition. Providers must offer suitable alternatives or backup power solutions.

What UK Businesses Must Do Before 2027

• Audit your phone lines: List all phone numbers, what they're used for, and whether they're published anywhere.
• Identify dependencies: Do you have alarm systems, card machines, fax machines, or door entry systems connected to phone lines? These need VoIP-compatible replacements or alternative solutions.
• Test your internet: VoIP quality depends on broadband. If your connection struggles with video calls, it'll struggle with VoIP. Consider upgrading to fibre.
• Plan the migration: Port your main numbers to VoIP for continuity. Choose a reputable provider with experience in business migrations.
• Communicate changes: If any phone numbers are changing, give customers, suppliers, and partners advance warning. Update all published materials.
• Train your team: Staff need to understand how VoIP works, especially if working remotely. Plan basic training sessions.
• Prepare for emergencies: If you operate in sectors where phones are safety-critical, implement backup power and failover internet.

The 2027 deadline is firm. Waiting until late 2026 means competing with millions of other businesses for provider attention, engineer time, and porting slots. Starting migration now ensures a smooth, pressure-free transition.

Frequently Asked Questions

Can I keep my existing phone number when switching to VoIP?

Yes, through a process called number porting. You can transfer your existing UK landline or VoIP number to your new provider. The process takes 5–10 working days and maintains your number throughout—there's no service interruption. You'll need your current provider's account details and authorisation code. Don't cancel your old service before the port completes, or you'll lose the number permanently.

Do VoIP numbers work without internet?

No, VoIP requires internet connectivity to function. If your broadband fails, calls won't work unless you have backup systems. Solutions include 4G failover routers that automatically switch to mobile data, or having staff use the VoIP mobile app over 4G when office internet is down. This differs from traditional landlines, which worked during power cuts because the phone network itself provided power.

Is VoIP cheaper than a landline?

Yes, typically 40–60% cheaper for businesses. Traditional landlines charge £15–£25 per line monthly, plus per-minute call costs. VoIP packages cost £8–£15 per user with unlimited UK calls included. You also avoid expensive PBX hardware purchases and maintenance. International calls are 60–80% cheaper through VoIP. The savings increase with business size and call volume.

Can you trace a VoIP phone number?

VoIP numbers are traceable to the provider and account holder through legal processes, similar to traditional phones. Law enforcement can obtain records with proper authorisation. However, VoIP numbers are easier to spoof—scammers can make calls appear to come from any number, including yours. Legitimate businesses using VoIP are fully traceable through their provider's registration and calling records.

Are VoIP numbers safe and secure?

When properly configured, VoIP is more secure than traditional phones. Calls areencrypted using SRTP and TLS protocols, making interception harder than unencrypted landline calls. Risks include account hacking if you use weak passwords—enable two-factor authentication and set strong credentials. Reputable providers include fraud detection to spot unusual calling patterns. For sensitive conversations, VoIP from established business providers is safe.

What is the difference between a VoIP number and a landline?

The key difference is infrastructure: landlines use physical copper wires connected to specific buildings, while VoIP numbers route calls over the internet and exist in the cloud. VoIP numbers work on any internet-connected device anywhere, whereas landlines only work where they're physically installed. VoIP offers advanced features like call recording, analytics, and mobile apps that landlines cannot match. Landlines are being phased out—the UK PSTN network shuts down completely in January 2027.

Can I use a VoIP number on my mobile phone?

Yes, through your VoIP provider's mobile app. Download their iOS or Android app, log in with your credentials, and you can make and receive calls using your business number on your personal smartphone. The app works over WiFi or mobile data (4G/5G). Customers calling you see your business number, not your personal mobile number, maintaining privacy. Most providers' apps also show your contacts, voicemail, and call history.

Do I need a physical phone for a VoIP number?

No, VoIP numbers work perfectly through software alone. You can use apps on computers, smartphones, and tablets without any desk phones. Many businesses operate entirely on softphones, especially remote teams. That said, desk phones remain popular in traditional office environments for comfort and professional appearance—most VoIP providers support IP desk phones if you prefer physical handsets.

How much does a VoIP phone number cost in the UK?

Number rental ranges from free (first number often included) to £2–£5 monthly per additional number. Toll-free numbers cost more, typically £5–£8 monthly plus 3–8p per minute for incoming calls. User licenses cost £8–£25 per person monthly, depending on features. Most packages include unlimited UK calling. A typical small business (5–10 users) pays £50–£150 total monthly for numbers, licenses, and calls—substantially less than equivalent landline costs.

Can VoIP numbers receive SMS messages?

Some VoIP providers offer SMS capability on certain number types, but it's not universal. Traditional UK landline-format numbers (01, 02, 03) don't normally support SMS because they weren't designed for text messaging. Mobile-style VoIP numbers (07) and some international virtual numbers may support SMS. If you need business SMS capability, verify this specifically with your provider—many offer it as a separate feature or through dedicated SMS platforms.

What happens to my VoIP number if the internet goes down?

Calls won't work during internet outages unless you have backup systems. Most business VoIP systems let you configure automatic failover—calls divert to mobile phones or alternative numbers when the system detects your connection is down. Staff can also use VoIP apps on smartphones over 4G when the office internet fails. For critical situations, 4G failover routers automatically switch to mobile broadband, keeping phones working even when the main internet drops.

Are VoIP calls recorded?

Only if you or your provider enables recording. Call recording is a feature many VoIP systems offer, but it's typically optional and must be activated deliberately. UK law requires you to inform callers if you're recording (usually an automated announcement at call start). Recordings are useful for training, quality monitoring, and dispute resolution. If you don't enable recording, VoIP calls are not recorded—they work like traditional phone calls.

Can emergency services trace my location with a VoIP number?

VoIP emergency calling works differently from traditional phones. When you set up VoIP, you register your primary physical address with each user account. When someone dials 999 or 112, emergency services receive this registered address. If staff work from multiple locations, the registered address may not reflect where they actually are when calling. Users should verbally confirm their location when calling emergency services from VoIP. This differs from mobile phones, which provide GPS location automatically.

What is the difference between a VoIP number and a virtual number?

These terms are often used interchangeably and mean essentially the same thing—a phone number that routes calls over the internet rather than traditional phone lines. "Virtual number" sometimes specifically refers to international numbers that route to different countries, or to numbers used purely for forwarding without dedicated devices. In practice, when someone says "virtual number", they usually mean a VoIP number, and vice versa.

How do I get a VoIP phone number in the UK?

1. Choose a VoIP provider (compare features, pricing, and reviews).
2. Select your plan and number of users.
3. Pick your phone number type—local geographic area code, national 03 number, or toll-free 0800.
4. Port your existing numbers or choose new ones from available options.
5. Configure your devices by downloading apps or setting up desk phones.
6. Test calling, set up routing, and train your team.

The entire process typically takes a few hours to a week, depending on whether you're porting existing numbers.

Conclusion: Why VoIP Numbers Are the Future of UK Business Phones

VoIP phone numbers aren't just a replacement for dying landline technology—they're a fundamental upgrade to how businesses communicate.

With the 2027 PSTN shutdown approaching, migration from traditional phone lines is mandatory, not optional. But rather than viewing this as forced change, smart UK businesses are recognising VoIP as an opportunity: lower costs, remote work enablement, advanced features previously available only to enterprises, and the flexibility to scale and adapt as business needs change.

Whether you're a solo consultant needing one professional number on your mobile, a growing startup adding staff weekly, or an established business preparing for the landline switch-off, VoIP numbers deliver capabilities traditional phones never could.

The technology is mature, the providers are established, the cost savings are real, and the deadline is fixed. Start planning your migration now, port your existing numbers to maintain continuity, and join the millions of UK businesses already enjoying the freedom of cloud-based telephony.

Your customers won't notice the difference—except perhaps that you answer more reliably, from more places, with better service than ever before.