How To Switch to VoIP Ahead of the Big Switch Off

The UK’s traditional landline network is being switched off by 31 January 2027, so any business still using the analogue PSTN network should start its (Voice over Internet Protocol) VoIP migration now.

The quickest way to switch to VoIP is to audit every phone line and connected device, check your broadband can support internet-based calls, choose a provider, port your numbers, train your staff, and test the new system before cancelling your old services.

We’ve updated this guide for the Big Switch Off timeline, and it reflects the latest guidance from Openreach, GOV.UK, and Ofcom in 2026, including the need to check alarms, payment terminals, lift lines, intercoms, broadband services, and other systems that may still depend on analogue lines.

What Has Changed About The Big Switch Off In 2026?

The Big Switch Off is no longer a distant telecoms issue. Openreach says the analogue network will be retired by 31 January 2027, and the UK Government is advising business customers to migrate at the earliest opportunity.

The biggest 2026 update is that businesses should now focus on hidden PSTN dependencies, not just replacing desk phones. Your office landline may also support systems that are easy to overlook, including:

• Fire, intruder and security alarms that dial out through an analogue line
• Lift emergency phones that need to keep working after the migration
• Older EPOS or payment terminals that still use a phone line
• Door entry, intercom and CCTV systems connected to legacy lines
• Fax machines, telemetry and monitoring equipment that may need replacing or reconfiguring
• Broadband services that still rely on traditional phone-line infrastructure

Ofcom also reminded providers in January 2026 that digital landlines will not work in a power cut unless there is a backup solution. This matters for sole traders, small offices with poor mobile signal, public-facing businesses, and any organisation that relies on a landline for emergency calls.

How Long Does It Take To Switch From Landline To VoIP?

Most small businesses should allow four to eight weeks to move to VoIP, but larger or more complex businesses should allow three to six months.

It’s certainly possible to migrate in a shorter time frame, especially for micro-businesses, but actioning things earlier will make the situation less stressful for you and your team.

Your timeline will depend on:

• Number of users: A five-person office can usually migrate faster than a multi-site business with call queues and departments.
• Number porting: Keeping your existing business numbers is normally possible, but it needs to be scheduled carefully.
• Connected devices: Alarms, lifts, payment terminals and monitoring systems may require separate supplier checks.
• Broadband quality: VoIP needs stable connectivity, so some businesses will need to upgrade broadband first.
• Training needs: Staff may need help using softphones, mobile apps, call transfers, voicemail and admin portals.

Do not plan your migration for the final weeks of 2026. Suppliers, engineers and number-porting teams are likely to be busier as the deadline gets closer.

1. Audit Every Phone Line And Connected Device

Estimated timescale: One to three weeks

Start by identifying every line, device and service that could be affected by the PSTN switch-off. This is the most important step because many businesses only think about desk phones, then discover later that alarms, lifts or payment systems also need attention.

Create an inventory that includes:

• All phone numbers used by your business, including main lines, direct dials and fax numbers
• All analogue and Integrated Services Digital Network (ISDN) lines, including any lines used rarely or only as backups
• All connected devices, such as alarms, lifts, intercoms, CCTV, EPOS terminals and monitoring systems
• Supplier details for telecoms, broadband, alarm, lift, payment and maintenance providers
• Contract end dates, notice periods and early termination fees
• Criticality, so you know which systems would cause the most disruption if they failed

Rank each item as high, medium or low priority. Customer-facing phone lines, alarms, payment systems and lift emergency phones should usually sit at the top of the list.

Once you have your inventory, contact each equipment supplier and ask whether the device will work on a digital phone line. Do not assume that analogue equipment will keep working through an adapter.

2. Check Your Broadband Can Support VoIP Calls

Estimated timescale: One to two weeks

VoIP calls run over the internet, so your broadband connection needs to be stable enough to carry voice traffic without delay, dropouts or poor call quality.

As a simple rule, allow around 100kbps per concurrent VoIP call. This means 10 simultaneous calls would need roughly 1Mbps of dedicated bandwidth, before accounting for other internet use, such as email, cloud software, video calls and file transfers.

When assessing your connection, check:

• Upload and download speed: VoIP needs reliable upload speed as well as download speed.
• Latency and jitter: Delays or unstable packet delivery can make calls sound broken or out of sync.
• Router quality: Your router should support Quality of Service (QoS), which prioritises voice calls over less urgent data.
• Wi-Fi coverage: Softphones and wireless handsets need strong coverage across the areas where staff take calls.
• Backup connectivity: A 4G or 5G failover connection can keep calls running if your main broadband fails.

If your business still relies on older broadband, ask your provider whether you should move to full fibre, Single Order Generic Ethernet Access (SoGEA), Ethernet or another business-grade connection before switching phones.

3. Choose The VoIP Setup That Fits Your Business

Estimated timescale: One to two weeks

The right VoIP setup depends on how your team works. Most small businesses will be best served by a hosted VoIP or cloud phone system, because the provider manages the core phone infrastructure off-site.

The main options are:

• Hosted VoIP: Best for SMEs that want a cloud-based phone system with minimal on-site hardware
• IP desk phones: Best for teams that still want a traditional handset experience
• Softphones: Best for hybrid teams that want to make and receive calls through laptops, mobiles or tablets
• SIP trunking: Best for larger businesses that want to keep an existing IP-enabled PBX while replacing ISDN lines
• Mobile-first VoIP: Best for field teams, remote workers, tradespeople and businesses without a fixed office

If your staff work across home, office and mobile settings, prioritise softphone apps, mobile call routing, call forwarding and presence indicators. These features help employees answer business calls from the right device without giving customers personal mobile numbers.

4. Compare VoIP Providers on Migration Support, Not Just Features

Estimated timescale: Two to four weeks

When choosing a top VoIP provider plan, look beyond the monthly price. The provider needs to help you migrate safely before the Big Switch Off, especially if you have multiple sites, existing phone numbers or non-phone devices connected to old lines.

Compare providers on:

• Number porting support: Check how the provider will move your existing numbers and what downtime to expect.
• Call quality and uptime: Look for reliable service, clear SLAs and strong customer support.
• Migration planning: Ask whether the provider can help audit your current setup and identify affected lines.
• Security: Look for encryption, secure login controls, user permissions and fraud prevention features.
• Integrations: Check whether the system connects with your CRM, helpdesk, Microsoft Teams or other business software.
• Scalability: Make sure you can add users, numbers, call queues and locations, without replacing the whole system.
• Support hours: Match support availability to your operating hours, especially if you serve customers outside nine to five.
• Total cost: Include licences, hardware, installation, call recording, analytics, international calls and contract terms.

Useful VoIP features include call forwarding, voicemail-to-email, auto-attendant menus, call queues, call recording, conference calling, analytics, IVR systems and CRM screen pops.

For a wider buying guide, read our guide to setting up VoIP for your business.

5. Plan Number Porting, Hardware And Integrations

Estimated timescale: Two to four weeks

Before your go-live date, confirm exactly what needs to be installed, configured or replaced. This includes handsets, headsets, routers, apps, call flows, integrations and number-porting dates.

For hardware, decide whether your team needs:

• IP desk phones for reception, sales teams, support teams or shared workspaces
• Headsets for call-heavy roles or staff using softphones
• Adapters where compatible analogue devices need a temporary bridge to digital services
• Upgraded routers and switches with QoS support for voice traffic
• Backup power or connectivity for sites that need stronger resilience

For software, configure:

• User accounts and permissions so staff only access the tools they need
• Call routing rules for departments, locations, opening hours and overflow calls
• Voicemail and voicemail-to-email for individual users and shared inboxes
• CRM integrations so calls can be logged against customer records
• Helpdesk integrations so support teams can link phone calls with tickets
• Collaboration integrations if your team uses tools such as Microsoft Teams or Slack

Schedule number porting for a quiet period where possible. Your new provider should explain what will happen before, during and after the port.

6. Test The VoIP System Before Moving Everyone Across

Estimated timescale: One to three weeks

Run a small pilot before switching the whole business. This helps you catch call-quality problems, routing mistakes and training gaps before customers are affected.

Your pilot should test:

• Inbound calls: Check main numbers, direct dials, call queues and out-of-hours messages.
• Outbound calls: Confirm caller ID, call quality and call permissions.
• Call transfers: Test warm transfers, blind transfers and transfers between devices.
• Voicemail: Confirm greetings, notifications and voicemail-to-email delivery.
• Mobile and softphone apps: Test calls on laptops, tablets and smartphones.
• Emergency calls: Confirm location information and escalation procedures with your provider.
• Integrations: Check whether call logs, customer records and tickets sync correctly.
• Connected devices: Test any alarms, payment terminals, lifts or monitoring systems that have been upgraded.

Document every issue and assign an owner. Do not move to full rollout until your most important call flows and connected devices have been tested.

7. Train Staff on the VoIP Tasks They Actually Use

Estimated timescale: One to two weeks

VoIP training should focus on real tasks, not every feature in the system. Most staff need to know how to answer calls, transfer calls, access voicemail, use softphones and escalate problems.

Cover the essentials:

• Making and receiving calls on desk phones, softphones and mobile apps
• Transferring calls to colleagues, departments and external numbers
• Managing voicemail, including voicemail-to-email and shared mailboxes
• Using call queues if staff work in sales, support or reception roles
• Changing availability so calls route correctly when staff are busy or away
• Reporting problems so IT or your provider can fix issues quickly

Use short written guides, screenshots, video demos and live Q&A sessions. It also helps to choose one VoIP “champion” in each department who can support colleagues during the first few weeks.

8. Manage the Changeover With a Backup Plan

Estimated timescale: One to two weeks

The changeover needs a clear date, a named owner and a fallback plan. The aim is to move calls to the new VoIP system without customers noticing the transition.

Before go-live:

• Confirm the number-porting date with your new provider and old provider.
• Tell staff what is changing, including when old phones will stop being used.
• Warn customers only if needed, such as if numbers, opening hours or support routes are changing.
• Set temporary call forwarding where possible, so calls can be redirected if the port is delayed.
• Keep IT and provider support on standby during the go-live window.
• Monitor key numbers immediately after launch to check calls are connecting correctly.

A phased rollout is safer for larger businesses. Start with one department or site, then move the rest once call quality, routing and support processes are stable.

9. Build in Security, Power Backup and Ongoing Support

Estimated timescale: Ongoing

VoIP needs ongoing management because your phone system now depends on internet connectivity, user accounts, software settings and provider support.

Your post-migration checklist should include:

• Security controls: Use strong passwords, multi-factor authentication where available, user permissions and call-spend limits.
• Software updates: Keep handsets, routers, apps and admin portals up to date.
• Call monitoring: Review call quality, missed calls, queue times and support tickets.
• Power resilience: Use battery backup or mobile failover if your business needs calls during power cuts.
• Emergency procedures: Make sure staff know what to do if internet, power or VoIP service fails.
• Supplier review: Keep records of telecoms, broadband, alarm, lift and payment-system suppliers.

Your team should also know how to report faults quickly, both internally and to your VoIP provider.