Migrating the UK’s critical national infrastructure (CNI) from ageing analogue networks to modern digital services could generate a net economic benefit of over £3 billion by 2040.
A study – conducted by Assembly Research and released today by BT – shows the immense financial, social, and environmental advantages of the transition while issuing a warning about the high cost of delay.
Data from UK telecoms regulator Ofcom shows that resilience incidents on the Public Switched Telephone Network (PSTN) have risen by 45%, making the decades-old system increasingly unreliable. The analysis highlights a “cost of inaction” amounting to £437 million for CNI customers who postpone the move.
“This research sends a clear message: delaying the shift to digital carries a real cost to public services, the environment and the wider economy,” said Jon James, CEO of BT Business.
“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.”
The findings – which evaluated energy, water, health, emergency services and local government – quantify substantial long-term gains for the UK from switching to digital services. The energy sector stands to gain the most, with a projected £1.4 billion benefit from improved resilience and better demand forecasting.
The water sector could see efficiencies worth £771 million through smarter network monitoring and reduced electricity usage. Local government is another beneficiary, with potential gains of £486 million driven by modernising telecare systems and cutting maintenance on old equipment.
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.”
Beyond the direct economic impact of switching to digital services, there are also welcome social and environmental returns for the UK. The transition is projected to save 3.42 megatonnes of carbon emissions, equivalent to powering every home in Birmingham for a year.
The shift to advanced digital telecare is also expected to prevent over one million emergency call-outs and 750,000 unnecessary ambulance trips by 2040, averaging more than 100 avoided journeys every day.
This migration will also free up vast amounts of staff time – including 12 million hours for council staff and over 600,000 hours for the National Health Service – comparable to the annual workload of 6,500 and 350 full-time employees, respectively. Moving away from legacy fire alarms could also prevent up to 280,000 false fire service callouts.
The UK’s transition to digital connectivity is a major national programme endorsed by Ofcom and the Government. While BT migrated nearly 300,000 legacy business lines in 2024 alone, the UK risks falling behind international peers. Countries like Germany and Spain are close to completing their migrations, while Italy, Portugal and France are actively pressing ahead.
The PSTN is set for full retirement in January 2027, and UK organisations are being urged to complete their migrations to digital services by the end of 2025 to avoid disruption.
See also: EE deploys world-first solution for slow 5G speeds in crowds
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