For many UK SMEs, the retirement of the traditional telephone network is still being treated as a telecoms upgrade: replace a phone system, port a few numbers and move on.
That approach is too narrow.
The retirement of the Public Switched Telephone Network (PSTN) and ISDN on 31 January 2027 is a wider infrastructure event. It affects Voice and Connectivity, site resilience, security, payment systems, alarms, emergency communications and the way technology expenditure is controlled.
The right response is not simply to buy a digital phone system. It is to review how communications support the business, then build the network and operational controls needed to make that strategy reliable.
The 2027 deadline is fixed
Openreach is retiring the UK’s traditional copper-based telephone network and moving voice services to an all-IP model. Traditional landlines, ISDN2, ISDN30 and other PSTN-dependent services must be migrated to digital alternatives.
Openreach’s guidance confirms that traditional phone lines will be switched off on 31 January 2027. The Openreach Big Switch-Off guidance advises businesses to act early, particularly where other devices are connected to telephone lines.
The scale of the remaining work is significant. In July 2026, Openreach warned that approximately 1.5 million UK analogue phone lines had yet to make the digital switch. For SMEs, that creates a clear risk: migration capacity, engineering appointments, compatible equipment and number porting services may all become harder to secure as the deadline approaches.
Leaving the decision until January is not a strategy. It is a queueing system.
Voice migration is a business infrastructure decision
A digital voice service depends on more than handsets. It relies on:
- Suitable broadband or leased connectivity
- Reliable switches, routers and firewalls
- Correct traffic prioritisation for voice
- Power to the network and telephone equipment
- Resilient failover arrangements
- Accurate number and user records
- Support processes for faults and service changes
This is why Voice and Connectivity should sit within a wider Network Solutions review rather than being handled as an isolated telecoms purchase.
A hosted VoIP platform may be appropriate for one organisation. Another may require SIP trunks into an existing phone system. A multi-site business may need separate connectivity paths, mobile failover or a more structured approach to call routing.
The question is not, “Which phone system should we buy?”
It is, “What communications capability does the business require, and what infrastructure will deliver it consistently?”
That is the role of a consultancy-first approach. The Fractal IT Director identity starts with the operating model, risk profile and commercial objectives. Voice, network management, hardware, licences, print and Helpdesk Support are then treated as bolt-on execution services that support the agreed strategy.
Audit every device connected to a phone line
The most common failure in PSTN migration is focusing only on the main office telephone system.
Many businesses have devices connected to analogue lines that are not visible in the IT department’s day-to-day systems. These may include:
- Intruder and fire alarm panels
- Lift emergency phones
- CCTV and remote monitoring equipment
- Payment terminals
- Fax machines
- Door entry systems
- Out-of-hours and night-service lines
- Legacy modems and telemetry devices
- Emergency call points
- Building management equipment
The UK Government guidance on moving landlines to digital technologies specifically highlights alarms, telecare devices, door entry systems, payment terminals, lifts, intercoms and broadband services as areas requiring review.
Every device owner or supplier should confirm:
- Whether the device currently uses PSTN, ISDN or an analogue line.
- Whether it supports the proposed digital service.
- Whether a new IP, 4G or 5G communicator is required.
- Whether the device needs a separate power supply or battery backup.
- How the service will operate during a broadband or power failure.
- Who is responsible for testing and ongoing support.
This is particularly important for alarms, lift phones and emergency systems. A phone number that appears on an invoice may be supporting a safety-critical function elsewhere in the building.
The audit should include every site, satellite office, warehouse, shop floor, medical room and unmanned location. A spreadsheet of telephone numbers is useful, but a dependency map is better: each number linked to its physical location, purpose, supplier, equipment and continuity requirement.
Start number porting four to six weeks before go-live
Number porting is one of the most visible parts of a voice migration and one of the easiest to underestimate.
Businesses should normally begin the porting process four to six weeks before the planned go-live date. The exact period depends on the provider, the complexity of the number range and whether there are historic records or address mismatches to resolve.
Before submitting a porting request, confirm:
- Main reception numbers
- Direct dial numbers
- Number ranges
- Departmental hunt groups
- Emergency and out-of-hours routing
- Numbers used on websites, invoices and customer literature
- Numbers associated with alarms, payment services or other devices
- Existing call recording and compliance requirements
A port can fail or be delayed because the account name, service address or number range does not match the provider’s records. In a multi-site organisation, seemingly minor discrepancies can create significant operational disruption.
Porting should therefore be part of a controlled project with a named owner, documented dependencies, test calls and a rollback or contingency plan. It should not be left to the day before installation.
Design for power failure and connectivity loss
Traditional telephone lines often provided power to basic handsets. Digital voice services usually depend on the local electricity supply, router, network equipment and broadband connection.
That changes the resilience calculation.
A sensible design may include:
- Uninterruptible power supplies for routers, switches and key voice equipment
- Secondary broadband or leased connectivity
- 4G or 5G failover
- Automatic call diversion to mobiles
- Pre-agreed emergency contact procedures
- Documented recovery steps for staff
- Regular testing of failover arrangements
This is where Voice and Connectivity meets Disaster Recovery. A business does not need an unnecessarily complex architecture, but it does need to understand the consequences of losing the primary connection.
For example, a small professional services office may be able to divert calls to mobiles for several hours. A healthcare provider, logistics operation or customer contact team may need a more structured continuity design with resilient connectivity and documented escalation.
The correct answer depends on business impact, not on the most impressive product specification.
Use Technology Expense Management to control the change
The switch-off creates an opportunity to examine technology expenditure rather than simply adding another monthly service.
A Technology Expense Management review should consider:
- Duplicate or unused telephone numbers
- Legacy ISDN and analogue line charges
- Broadband services that no longer match operational requirements
- Mobile contracts used as informal failover
- Separate support agreements for phones, networks and connected devices
- Hardware nearing end of life
- Unused user licences
- Call recording, contact centre or collaboration features that are not being used
- Supplier overlap across multiple locations
The objective is not to minimise every cost. It is to ensure each cost has a purpose, an owner and a measurable contribution to the business.
This is also where wider Cloud Solutions planning may be relevant. Moving voice to the cloud can support flexible working and faster changes, but it does not remove the need for network capacity, security, support or continuity planning.
The same principle applies to other strategic projects. A Dynamics 365 Jump Start programme, for example, should not be treated as a software installation in isolation. Its success will depend on identity, connectivity, user support, data, process design and operational ownership. Voice migration deserves the same level of joined-up thinking.
What about legacy platforms?
Some organisations still operate important line-of-business platforms that require careful connectivity and infrastructure planning. Where IBM i, Power Systems or AS/400 environments are present, the voice migration should be assessed alongside the wider estate rather than treated as an unrelated telecoms project.
Specialist IBM i Management may be required to understand dependencies, access arrangements, remote support and business continuity around legacy platforms.
The principle is consistent: preserve what remains valuable, modernise what creates risk and avoid introducing change without understanding the operating environment.
A practical SME action plan
UK SMEs should complete the following steps well before 31 January 2027:
- Identify every PSTN, ISDN and analogue service.
- Map each line to the device, site and business process it supports.
- Contact alarm, lift, payment, CCTV and building-system suppliers.
- Assess broadband capacity, firewall capability and local network quality.
- Choose the digital voice model based on business requirements.
- Confirm number ranges, porting requirements and go-live dates.
- Begin number porting at least four to six weeks before go-live.
- Install power backup and connectivity failover where the business needs it.
- Test calls, hunt groups, emergency routing and non-voice devices.
- Document support ownership, recovery procedures and supplier contacts.
- Review the full estate through Technology Expense Management.
- Give staff clear instructions before the migration takes place.
For organisations coordinating communications across offices, premises and wider operational suppliers, the Evestaff group gateway provides access to the broader group of services.
The strategic conclusion
The 2027 switch-off is not simply the end of an old telephone network. It is a test of whether an organisation understands its dependencies.
A rushed VoIP installation may provide a dial tone while leaving alarms, lift phones, payment terminals, out-of-hours services and recovery procedures unresolved. A strategy-first review produces a more useful result: communications aligned with business operations, resilient Network Solutions, controlled technology expenditure and support that remains practical after go-live.
Managed IT Services, Helpdesk Support and voice execution all have a role. They are the mechanisms that deliver the strategy, not substitutes for it.
UK SMEs should begin now, while there is still time to audit, design, port, test and correct. On 31 January 2027, the old network will not negotiate.
SEO tags: Voice and Connectivity, Network Solutions, PSTN switch-off 2027, ISDN switch-off, digital voice UK, VoIP for SMEs, Cloud Solutions, Managed IT Services, Helpdesk Support, Technology Expense Management, Disaster Recovery, Dynamics 365 Jump Start, IBM i Management
Join The Discussion