The Big Switch Off: Everything UK Businesses Need to Know About the 2027 Deadline 

What Is the Big Switch Off?

The big switch off, also referred to as the big switchover and the great big switch off,  represents the complete shutdown of the UK's traditional copper line network. This analogue legacy platform uses underground copper wires to enable communication, but this hardware can no longer sustain modern requirements and is becoming increasingly fragile and prone to failure.

The BT big switch off means transitioning from analogue  technology to a fully digital VoIP  (Voice over Internet Protocol) system. Every phone line in the UK will become digital, with calls routed over an internet connection rather than through traditional copper  infrastructure. This represents the most significant change to British telecommunications since the original telephone line network was established over a century ago. 

Several critical factors are driving the BT switch-off. Ofcom's recent Connected Nations report highlights that in 2024, the number of significant PSTN resilience incidents reported increased sharply by 45%. The ageing copper network simply cannot meet modern communication demands, with maintenance costs spiralling as engineers struggle to source replacement parts for obsolete equipment. 

The introduction of mobile phones and internet-based services for customers will cause the PSTN network to become an obsolete technology. Because telcos cannot continue to support two networks, they are switching to an all-digital network model.

BT Openreach has invested heavily in deploying full fibre networks throughout the UK and does not have the financial resources necessary to continue supporting outdated technology while developing a new technology solution. 

Some countries, such as Estonia and the Netherlands, have completely converted from landline to digital switchover; others, such as Germany, Japan, and Sweden, have outpaced the UK in their move to a more effectively managed digital telephone network. As a result, the UK phone number shutdown aligns with the global telecommunications industry's shift to a strictly digital marketplace, allowing UK businesses to remain competitive in a rapidly changing digital world. 

Businesses Using Traditional Phone Systems

Any organisation relying on landline infrastructure faces an impact from the PSTN switch-off. This includes small businesses using traditional desk phones, companies with ISDN2e or ISDN30 lines, organisations with PBX systems connected to copper lines, and businesses in stop sell areas unable to order new analogue services. The transition affects enterprises of all sizes, from sole traders to large corporations with multiple sites.

Services and Devices That Will Stop Working

The big switch off doesn't just affect telephone calls. Multiple critical systems rely on PSTN connectivity. Traditional landline telephones, fax machines, analogue phone equipment, and legacy PBX systems will all cease functioning. Building alarm systems connected to phone lines, CCTV systems using analogue connections, door entry systems, and lift phones for emergency communication will require immediate attention.

Payment processing presents another significant concern. Card machines that use phone line connectivity, often referred to as PDQ machines or EPOS machines, must be replaced with IP-enabled alternatives. Many retail and hospitality businesses remain unaware that their payment infrastructure depends on PSTN connectivity until it fails.
 

Healthcare providers face particular challenges. Telecare devices, medical monitoring equipment, and personal emergency alarms all require careful assessment and upgrading. These systems often serve vulnerable customers whose safety depends on reliable emergency communication, making this aspect of the migration especially critical.

If any of these systems connect via your landline, they require upgrading before the PSTN switch-off dates. Conducting a comprehensive audit now prevents nasty surprises later.

Operational Impact on Businesses

Businesses still reliant on traditional services will find themselves unable to make or receive calls, causing severe disruption. Without proactive migration, you face complete loss of telephone service, failed alarm and security systems, non-functional payment processing, disrupted customer communication, and potential loss of your existing business number. The consequences extend beyond mere inconvenience many organisations would find their operations grinding to a complete halt.

The Cost of Inaction to The Big Switch Off

A survey revealed that 45% of UK businesses are unaware of the great big switch off, and 62.1% are still using landlines or old analogue lines despite Openreach plans to cut off service. Perhaps most concerning, 72% of UK businesses surveyed did not see the PSTN switch-off as a priority. This widespread complacency creates significant risk for thousands of organisations.

Delaying your transition risks last-minute installation delays, power cut vulnerability without backup solutions, higher migration costs during peak demand, service interruptions affecting customer trust, and the inability to order replacement equipment. As the deadline approaches, provider capacity will become constrained, potentially leaving late movers without viable options.

What Is VoIP?

VoIP (Voice over Internet Protocol) is the digital replacement for traditional landline systems. VoIP for business transmits voice calls over your internet connection rather than copper wires, offering superior functionality and reliability. This technology has matured significantly over the past decade, with millions of businesses worldwide now relying on VoIP as their primary communication platform.

Benefits of Cloud Phone Systems

Cloud phone system technology provides significant advantages over traditional telephone systems.  Cost efficiency represents a major benefit businesses typically save 30-50% on ongoing telecommunications costs through lower operational expenses, reduced maintenance requirements, elimination of separate voice and data networks, and decreased equipment costs.

Flexibility and mobility transform how modern businesses operate. Employees can make and receive calls from any device, work from anywhere with an internet connection, and use mobile app integration for remote teams. This digital technology capability proved invaluable during recent years when remote working became essential for business continuity.

Advanced features include video conferencing capabilities, integration with business applications like CRM systems, call recording and analytics for quality management and training, and auto-attendant and intelligent call routing. These tools were once available only to large enterprises with substantial budgets, but are now accessible to businesses of all sizes.

VoIP phone systems offer future-proof infrastructure compatible with emerging digital services, regular software updates that add functionality without hardware changes, and no obsolescence concerns that plagued traditional PBX systems.

VoIP vs Traditional Landlines

The distinction between old and new technology is clear. Old-style analogue phone lines have many limitations. They are restricted to a set location to operate; they only offer basic calling features, require a large financial investment to grow, are limited by poorly maintained connections for analogue telephone services, and do not offer much to connect with other business tools.

In contrast, Voice over Internet Protocol or VoIP solutions have several advantages. You can use VoIP anywhere through the Internet and have advanced collaboration tools; you can quickly and cost-effectively add more phone lines; VoIP runs on modern technology that is supported; and VoIP integrates with other business tools such as Customer Relationship Management (CRM) software, e-mail and many others.

The VoIP Shop's 6-Step Process: How to Migrate from PSTN/ISDN Phone Lines to VOIP/CLOUD Phone Systems

At The VoIP Shop, we've developed a proven methodology to ensure seamless transitions from PSTN/ISDN to Digital Voice. Our structured approach eliminates guesswork and ensures successful outcomes.

Step 1: Discovery & Consultation involves assessing your current infrastructure, understanding your business requirements, and identifying all affected systems. We conduct thorough site surveys to ensure nothing is overlooked.

Step 2: Solution Design sees our experts designing a tailored VoIP solution matching your operational needs and budget. We consider not just your current requirements but anticipated growth and changing needs.

Step 3: Infrastructure Preparation ensures your network and internet connectivity meet requirements for optimal voice quality. This may involve broadband upgrades or network configuration changes.

Step 4: Installation & Configuration includes professional installation of your new cloud phone system, including all devices and integrations with existing business applications.

Step 5: Testing & Training provides comprehensive testing of all features, plus staff training to maximise your investment and ensure everyone feels confident using the new system.

Step 6: Go-Live & Support ensures a smooth transition to your new system with ongoing technical support and monitoring. We don't disappear after installation; our team remains available to address any concerns.

Learn more about our migration process

Financial Considerations and ROI

Migration Costs and Long-Term Savings

PSTN to VoIP transition expenses include new phone equipment, installation and configuration, staff training, and potential network upgrades. However, these represent one-time investments that deliver ongoing returns. Newer tech, like VoIP, is actually much cheaper to run than PSTN lines. Businesses typically save 30-50% on ongoing telecommunications costs through lower per-minute charges, reduced maintenance, elimination of separate voice and data networks, and decreased equipment costs.

Early migration prevents inflated costs as demand peaks approach the deadline. Businesses delaying until 2026 will face limited provider availability, higher installation charges, extended wait times, and rushed implementations, increasing error risk. Acting now ensures you secure competitive pricing and adequate time for proper planning and testing.

Bandwidth and Network Configuration

Adequate internet speed is crucial. Each concurrent voice call requires approximately 100kbps bandwidth. Calculate your needs based on maximum simultaneous calls10 concurrent calls require 1Mbps minimum, 25 calls need 2.5Mbps, and 50 calls require 5Mbps. Add buffer capacity for other internet usage to prevent quality degradation during peak periods.

Optimal VoIP performance requires Quality of Service prioritisation, ensuring voice packets receive priority, VLAN segmentation for voice traffic, separating it from data, sufficient router capacity to handle packet processing, and proper firewall configuration allowing VoIP traffic without creating security vulnerabilities.

Compatible Devices

Digital phone equipment includes IP desk phones ranging from basic models to executive handsets, softphones, which are computer applications providing full functionality, mobile apps enabling staff to use business numbers on personal devices, conference phones for meeting rooms, and wireless headsets for staff who need mobility. The VoIP Shop provides comprehensive hardware solutions compatible with your chosen system, ensuring you have the right tools for your specific requirements.

With the PSTN switch-off approaching, proactive businesses are already reaping the benefits of digital communications. Don't risk becoming part of the last-minute rush.

Download Your Free Guide: The Ultimate Guide to the BT Landline Switch Off January 2027 provides a detailed timeline and milestones, technical specifications, vendor selection criteria, implementation checklists, and cost analysis frameworks.

Get Your Free Quote: Request your Quote to migrate from analogue to a Digital VoIP Phone System. Our experts will assess your requirements and provide a no-obligation migration proposal tailored to your business.