In January 2026, the UK Space Agency issued a request for information on behalf of the Home Office’s Emergency Services Mobile Communications Programme. The question it was asking, in essence, was whether direct-to-device satellite technology could help solve a problem that has been building for more than a decade: the Emergency Services Network is still not ready, Airwave is still running, and rural and coastal coverage gaps remain unresolved.
It is an important question, and not a straightforward one. Having spent thirty years working in RF and satellite communications — and having explored LEO satellite connectivity as part of my research for a TEDx talk in 2023 — I want to look at this carefully, because the gap between what D2D can do today and what mission-critical public safety communications actually requires is significant. Closing that gap is the real engineering and policy challenge.
Key context:
ESN original go-live target: September 2017
Current expected delivery: December 2029 at earliest
Combined Airwave + ESN programme cost to date: approximately £11 billion (NAO)
Users dependent on Airwave: over 300,000 frontline personnel
UKSA D2D RFI issued: January 2026, on behalf of Home Office ESMCP
Ofcom D2D framework in force: 25 February 2026
What the ESN Actually Is — and Why It Matters
The Emergency Services Network is the programme intended to replace Airwave, the UK’s current critical communications network for police, fire and ambulance services. Airwave runs on TETRA — Terrestrial Trunked Radio — an ETSI digital standard designed specifically for public safety use. It was built to be resilient, secure, and reliable. In those terms, it has delivered: Airwave provides more than 99 percent geographic coverage across the UK landmass and has a track record of operation in the most demanding conditions.
The problem is that TETRA is a narrowband technology, designed primarily for voice and low-rate data. ESN was conceived to replace it with a broadband 4G LTE platform — delivered by EE under contract — that would give emergency services personnel access to video, high-speed data, and modern application-based tools alongside voice. The programme was originally contracted in 2015 with a target completion date of September 2017.
That date has now slipped by more than a decade. The current official delivery date is December 2029, and even that is not guaranteed: Motorola, which was a key supplier before prematurely ending its involvement, publicly questioned whether 2029 was realistic. Airbus, which remains involved in TETRA infrastructure, has described the legacy system as likely to remain in use until at least 2035 as a backup. In April 2026, a further £25 million no-bid contract extension was issued to keep Airwave operational, with the Police Digital Service stating that the extension was needed to ensure public safety agencies could remain fully operational until ESN is ready. The total combined cost of supporting Airwave while building ESN has reached approximately £11 billion over the past decade, according to the National Audit Office — with ESN itself running roughly £3 billion over budget.
Where D2D Satellite Enters the Picture
One of the persistent problems with ESN — even setting aside the delays — is terrestrial coverage. EE’s 4G network covers the vast majority of the UK population, but population coverage and geographic coverage are very different things. Rural Scotland, coastal areas, upland terrain, and remote stretches of motorway all represent locations where terrestrial 4G infrastructure is absent or unreliable. For commercial mobile users, a dropped call is an inconvenience. For a police officer, firefighter, or paramedic in a remote location, it is a serious operational risk.
The UK Space Agency’s January 2026 request for information asked industry how satellite D2D technology — specifically LEO-based direct-to-device services — could augment the ESN to provide coverage in remote areas and locations that are challenging to serve using standard terrestrial infrastructure. It is a coverage gap problem, and D2D has been positioned as a potential solution.
The timing was deliberate. Ofcom’s D2D authorisation framework came into force in February 2026, removing the regulatory barriers to satellite-to-handset connectivity in UK mobile spectrum bands. The two early adopters — VMO2 with SpaceX Starlink, and VodafoneThree with AST SpaceMobile — are both building commercial services in the same timeframe. The UKSA’s RFI was effectively asking: can what is being built for the commercial market be adapted for mission-critical public safety use?
The Candidate Operators
Three operators were identified as the most relevant candidates in reporting around the UKSA RFI:
SpaceX Starlink is the most commercially mature D2D provider, with an operational direct-to-cell service already running in the United States in partnership with T-Mobile. In the UK, BT Group — the parent company of EE, which holds the ESN network contract — signed a broadband agreement with Starlink in 2025, making the relationship between the two organisations already established. That pre-existing commercial relationship makes Starlink a credible near-term candidate for any satellite extension to ESN.
AST SpaceMobile, partnered with VodafoneThree in the UK, is targeting broadband-grade LEO D2D with its BlueBird constellation. Its next-generation satellites are designed for peak speeds of up to 120 Mbps per coverage cell, which is substantially higher throughput than current D2D competitors. However, the constellation is still building toward continuous coverage; in early 2026 the service is intermittent, dependent on satellite overpass windows.
Eutelsat OneWeb, a UK-backed LEO operator with a government connection through the UK’s prior equity stake in the company, was also noted as developing D2D capabilities alongside its existing enterprise and government connectivity offerings.
Why Mission-Critical Is a Different Problem
Here is where the engineering challenge becomes serious. Commercial D2D services are being built to augment terrestrial mobile networks — to provide a basic fallback for consumers in areas without coverage. Mission-critical public safety communications have requirements that go considerably further, and which current commercial D2D services do not yet meet.
Availability and resilience
Airwave’s 99 percent-plus geographic coverage is not just a number — it is a guarantee that underpins operational planning. Emergency services personnel need to know, not hope, that communications will work. LEO D2D coverage is currently intermittent: service is available when a satellite is overhead, which in a LEO constellation at around 550 km altitude means overpass windows of roughly 5 to 10 minutes, with gaps between passes. The gap to continuous coverage depends entirely on constellation density. SpaceX’s Starlink has the scale to approach continuous LEO coverage in mid-latitudes, but continuous LEO coverage and the guaranteed availability of a mission-critical network are not the same thing.
Voice capability
TETRA was built for voice. It delivers push-to-talk group communications that are the operational backbone of how emergency services personnel communicate. Current commercial D2D deployments are primarily SMS and basic data. Voice services over D2D are planned and developing, but are not yet consistently available across the commercial deployments. Any ESN satellite extension would need voice as a baseline requirement, not a roadmap item.
Group communications
One of TETRA’s defining capabilities is trunked group call — the ability for multiple users to communicate simultaneously in a coordinated group, with dynamic talk group management, priority access, and pre-emption. These are features designed specifically for emergency service operational structures. Standard cellular networks do not natively replicate this model, and neither do current D2D satellite services. The ESN programme has had to address this through additional software layers on top of LTE; any satellite extension would need to address it too.
Security and encryption
Airwave uses proprietary encryption certified for law enforcement and emergency service use. Communications must be secured against interception, jamming, and spoofing in a way that commercial consumer D2D services are not designed to guarantee. Integrating satellite D2D into a mission-critical security architecture is a non-trivial systems engineering problem.
Device certification
Emergency service devices are certified and managed to a standard that commercial smartphones are not. The ESN programme is built around purpose-built handsets and device management frameworks. A D2D satellite service that works on consumer smartphones does not automatically work on a certified ESN device — the chipset and software stack need to support D2D, and the device needs to meet the programme’s security and operational requirements.
The core tension: D2D satellite in 2026 is being built as a consumer coverage supplement. ESN needs a mission-critical communications layer. Those are not the same design target, and closing the gap between them requires deliberate engineering and procurement effort — not just turning on a commercial service.
What D2D Could Realistically Contribute to ESN
None of this means satellite D2D has no role in the ESN architecture. It means the role needs to be accurately scoped.
The most credible near-term contribution is as a non-primary coverage supplement in genuine not-spots — the rural upland and coastal areas where terrestrial 4G will never reach economically. In those locations, even intermittent satellite connectivity for data and messaging would represent a capability improvement over nothing. If a police officer in a remote glen can send a message or receive an update between satellite passes, that has operational value even if it does not replace the continuous voice capability of a TETRA radio.
The longer-term vision is more ambitious: as LEO constellations mature, as voice over D2D matures, and as device ecosystems develop, satellite connectivity could become a genuine second layer for the ESN — providing resilience in the event of terrestrial outage as well as coverage in permanent not-spots. That is the scenario the UKSA’s RFI was exploring. But the timeline for all of those components to be ready simultaneously, certified for mission-critical use, and integrated into the ESN programme is measured in years, not months.
The TETRA Comparison
It is worth being direct about one thing that often gets lost in reporting on this topic: TETRA is very good at what it does. Its geographic coverage, resilience, group call capability, and operational track record are the benchmark against which any replacement or supplement must be measured. The reason Airwave is still running in 2026, a decade after its planned retirement date, is not only because ESN has been delayed — it is because TETRA’s performance in mission-critical scenarios has made the emergency services understandably reluctant to accept anything less.
D2D satellite services are not yet TETRA equivalents. They are a different kind of technology solving a different primary problem. The question the UKSA RFI was asking is whether they can be developed and certified to fill specific gaps in the ESN architecture — and that is a legitimate question worth pursuing carefully.
Final Thoughts
The UK’s emergency services face a communications infrastructure problem that is simultaneously a legacy issue, a programme management failure, and a genuine technology challenge. The ESN is more than a decade late, Airwave is still running on extended contracts, and rural coverage gaps remain unresolved. D2D satellite has been correctly identified as a potential tool for addressing those coverage gaps, and the UKSA was right to issue a request for information when it did.
But the engineering gap between commercial D2D as it exists in early 2026 — primarily SMS and basic data, intermittent coverage, consumer device focus — and what mission-critical public safety communications actually requires is real and should be stated clearly. Continuous availability, voice, group communications, security certification, and device compatibility are not optional features for emergency service use. They are the baseline.
The most honest assessment is that D2D satellite can contribute to the ESN architecture, but as a carefully scoped supplement in genuine coverage gaps rather than a wholesale alternative communications layer. Getting from here to there requires deliberate engineering investment, programme integration work, and realistic timelines — not just the arrival of a commercial service that happens to work on smartphones.
Craig Miles
RF and satellite systems engineer with 30 years spanning aerospace, satellite programmes, and wireless communications. TEDx Brayford Pool 2023. Founder, Yesway Communications Ltd.
Helping organisations understand wireless, RF & satellite communications — Advisor · Trainer · Consultant
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