BT has released new economic modelling from Assembly Research highlighting some of the financial, societal and environmental benefits of moving the UK’s Critical National Infrastructure (CNI) sectors from outdated analogue networks to digital infrastructure. The study finds a £3 billion net economic benefit could be realised across five key sectors by 2040.
The research evaluated the costs, risks and potential gains from digital migration across energy, water, health (NHS), emergency services and local government. It accounted for the direct cost of upgrading, as well as the rising expense of maintaining legacy systems like the Public Switched Telephone Network (PSTN) and the 2G mobile network – both decades old and increasingly challenging to support. Ofcom data shows resilience incidents on the PSTN have risen by 45%, underscoring the urgency of change.
Beyond the financial case, the modelling shows clear societal and environmental benefits by 2040, including:
Preventing 750,000 unnecessary ambulance trips – averaging more than 100 avoided journeys every day.
Freeing up 12 million hours of council staff time – equal to around 6,500 staff working full-time for a year.
Saving over 600,000 NHS staff hours – comparable to the annual workload of 350 full-time employees.
Avoiding up to 280,000 false fire service callouts as businesses move away from legacy fire alarms – equivalent to 54 false alarms every day.
Cutting 3.42 megatonnes of carbon emissions – equal to powering every home in Birmingham for a year.
Looking ahead, the benefits of digital migration are projected to bring significant improvements across the UK’s critical infrastructure. For the energy sector, digital networks can deliver improved resilience, help prevent outages, and enable more accurate demand forecasting – translating to an estimated £1.4 billion in savings. In the water sector, smarter network monitoring and reduced electricity usage could generate efficiencies worth £771 million.
Local governments, often under pressure to do more with less, stand to gain £486 million by modernising telecare systems and cutting the cost of maintaining ageing analogue equipment. In the NHS, digital transformation promises better call handling and more efficient emergency response. Meanwhile, emergency services could see fewer false alarms and improved call management, enabling faster, more targeted responses.
Jon James, CEO of BT Business, said: “This research sends a clear message: delaying the shift to digital carries a real cost to public services, the environment and the wider economy. Legacy systems are becoming increasingly unreliable, and the case for action is urgent. BT is committed to guiding the UK’s critical national infrastructure sectors through this upgrade with the resilience and support they need.”
Matthew Howett, Founder & CEO of Assembly Research, added: “For the first time, we’ve lifted the lid on legacy network migration and worked to understand the scope and scale of how key UK industries are still relying on aging fixed and mobile networks. Our research found that while the energy and water sectors are already well into their migrations, it’s vital that others follow to avoid growing costs and missed efficiencies.”
The UK’s transition to digital connectivity is a major national infrastructure programme endorsed by Ofcom and the Government. The Public Switched Telephone Network will be fully retired in January 2027, with businesses and public services urged to complete their migrations by the end of 2025 to avoid last-minute disruption.
In 2024 alone, BT migrated nearly 300,000 legacy PSTN business lines. Yet many CNI providers in the UK still rely on ageing analogue systems for critical operations, while other countries are moving faster. Germany and Spain are close to completing their migrations, and Italy, Portugal and France are actively pressing ahead. Against this backdrop, the UK risks falling behind its peers unless the pace of migration accelerates.
