Ofcom Update Guidance on Power Backup and Resilience in UK Mobile Networks

The UK telecoms and internet content regulator, Ofcom, has published a revised guidance document on network resilience, which was first published in 2024 (here) to give broadband, mobile and other digital network providers greater clarity on how they can “reduce the risk of network outages“. The new update clarifies their stance on power backup for mobile cell / mast sites.

Communications providers in the UK currently have a legal duty to identify, prepare for and reduce the risk of anything that compromises the availability, performance or functionality of their networks. The original guidance was thus intended to provide public network operators with greater clarity on how they could comply with their duties for security and resilience.

The hope is that this would serve to reduce the chances of serious and protracted network outages occurring, or at least make them quicker to resolve. But modern networks are complex beasts that can fail due to all sorts of reasons (it’s often the ones you don’t foresee or expect that bite the hardest). In addition, the 2024 guidance left open the question of precisely what measures mobile operators should take to mitigate against the risks of power outages.

The specific issue of improving power backup for Radio Access Networks (RAN) is not an easy one to resolve, with a number of UK mobile operators being known to have balked at the potential costs of deploying national battery backup (here and here); costs that could potentially work their way into higher retail prices for consumers.

Nevertheless, Ofcom has today published a 2026 revision of their Network and Service Resilience Guidance for Communications Providers (PDF), which among other tweaks now includes some clarifications on the regulators “expectations for mobile network operators’ backup power arrangements in the RAN“.

ISPreview had to do a bit of a before vs after comparison to find some of the changes (they weren’t clearly signposted), but this bit of new text below did stick out. Back in 2024 the same section was largely blank, pending the need for more studies, which have since taken place.

Power backup in mobile RAN sites

In the case of mobile cell sites, in order to meet their duties, including under Regulation 3 to take appropriate and proportionate measures to ensure the network is designed and constructed in a manner which reduces the risks of security compromises occurring, we expect MNOs to take robust measures to manage and mitigate against the risks of power outages and support continued communications services during power outages and surges which might reasonably be expected to occur. The measures we expect for mobile cell sites include the following parts of this guidance:

• our expectation that all communications providers maintain an ongoing programme of risk assessment and to make plans and investments commensurate with the identified risks, taking into account both the likelihood of events and the impact of their occurrence (3.2), which could include considering communities that may be particularly vulnerable to the effects of a power failure in the mobile RAN.

• on access sites and equipment where a significant number of customers’ last-mile connections are aggregated, resilience of the equipment and all key dependencies should be considered in the site and equipment design (see section 1.3.4). Where possible, communications providers should seek to eliminate loss of key dependencies, including mains power and network timing/synchronisation, for a significant period of time bearing in mind that citizens depend on the access network for access to emergency services (4.2.1).

We should point out that mobile operators have, in the background, been busy looking at this problem and making changes where viable. For example, last year saw Vodafone kick-off a new “Enhanced Power” initiative (here), which will work to boost resilience and extend power backup time at around 10,000 key mobile sites across Europe and Africa using a mix of AI and other technologies (specific plans for the UK were not disclosed).

Ofcom’s latest tweaks to this guidance seem to avoid being too prescriptive with their expectations, but the changes do still seem designed to give mobile operators more clarity and a bit of a nudge to take some greater action.