Shared indoor mobile infrastructure is a single in-building system that delivers 4G and 5G service from all mobile operators throughout a commercial property. In the telecoms industry this arrangement is called a neutral host model: an independent party builds and operates the infrastructure, holds no spectrum licence and serves no subscribers of its own, and every operator connects to it to reach their customers inside the building. For the people in the building, the effect is simple. Phones work on every network throughout the building, and nobody has to think about why.
The problem it exists to solve
Around 80% of mobile data traffic is generated indoors (Ericsson Mobility Report), yet mobile networks are planned and built for outdoor coverage. Modern energy-efficient buildings block much of the outdoor signal, and the higher frequencies used by 5G penetrate buildings even less than 4G did. The result is a structural gap: the places where people use their phones most are the places the networks reach worst.
Closing that gap building by building runs into an economic problem. No single operator can justify funding dedicated infrastructure in every commercial property for the benefit of only its own subscribers, and no landlord wants to manage separate agreements and installations for every network its tenants happen to use. The building needs one system that serves everyone, funded and run by a party whose incentives are aligned with the building rather than with any one operator. That party is the neutral host.
How the model works in practice
The infrastructure itself is a building-wide system of small cells, compact radio units distributed throughout the property and connected over fibre and Cat6 cabling, engineered to provide consistent 4G and 5G coverage across floors, cores, lifts and basements. The system connects back to the mobile operators through dedicated fibre, giving the building its own capacity rather than a share of whatever the nearest street mast can spare.
Operators join the shared system rather than building anything themselves. Depending on their preference, they integrate through their own base station equipment or digitally over fibre, retaining full control of their spectrum and service parameters within infrastructure they did not have to fund. The neutral host manages the system end to end, including 24/7 monitoring, and remains the single point of contact for the property owner, who signs one agreement instead of one per operator.
The model works because of its neutrality: since the host holds no spectrum and competes with no operator, every network can connect on equal terms, and the building owner is never locked to a single provider’s coverage footprint. Investment decisions follow the building’s performance needs rather than any operator’s commercial priorities.
Who pays, and what it replaces
Commercial models vary across the market, but the direction of travel is that indoor connectivity is becoming part of a building’s infrastructure, financed like other building services rather than as telecoms capital projects. In Proptivity’s model the infrastructure is delivered against a monthly service fee, shifting the property owner’s cost from upfront capital expenditure to a predictable operating cost, with design, installation and operation handled by one party.
The model replaces two older approaches. The first is doing nothing and relying on outdoor signal leaking in, which modern construction has quietly broken. The second is the legacy generation of in-building systems, coax-based distributed antenna systems designed in an era of voice and light data, which struggle with 5G capability and, being passive, cannot be remotely monitored. Compared with legacy active DAS, modern small cell systems reduce power consumption by up to 70% and equipment footprint by up to 80% (Ericsson), which is why they align naturally with the sustainability requirements now standard in commercial property.
What it means for property owners
For a landlord, the practical outcomes are reliable mobile performance as a marketable feature of the building, a single agreement and contact instead of a patchwork of operator relationships, and infrastructure that supports certification schemes such as WiredScore. Tenant expectations have moved: mobile connectivity that simply works has become part of what a premium workspace means, alongside air handling and lifts, and buildings increasingly compete on it. Dedicated infrastructure also carries the building’s own systems, from payment terminals to sensors and safety communications, on connectivity the owner actually controls.
What it means for operators
For operators, shared infrastructure converts indoor coverage from an unaffordable capital problem into an access decision. Ready-installed, independently funded systems let them extend high-quality service into buildings they could never justify equipping alone, improving customer experience precisely where usage is heaviest. Integration on their own terms, with control over spectrum and parameters preserved, has been the condition for operator participation, and modern platforms are built around it.
Why regulators are paying attention
Regulators across Europe have begun treating indoor coverage as a policy question rather than a private inconvenience, and shared models feature prominently in that discussion because they improve coverage while reducing duplicated equipment, energy use and street-level clutter. Ofcom’s discussion paper Mobile connectivity you can count on examines indoor performance expectations in the UK, and industry bodies such as the Telecom Infra Project are standardising how neutral host systems are specified and procured. The direction across markets is consistent: shared infrastructure is becoming expected practice rather than a novelty.
Seeing the model in a real building
The clearest way to understand shared indoor mobile infrastructure is through deployed examples, and our project pages describe live installations across Stockholm, Oslo and London, with the owners and operators involved. If the more immediate question is how your own building performs today, our free coverage check uses real-world mobile measurement data for your address, and our team prepares a full indoor coverage assessment at no cost and with no obligation.