Signal and coverage
What a coverage map is really showing you, why one room behaves differently from the rest, how congestion differs from weak signal, and the only evidence that settles your own address.
Sections on this page
The facts
- Type
- A computer prediction
- Models
- Outdoor signal
- Built from
- Terrain, mast positions, transmit power
- Cannot know
- Your walls or your local mast’s load
What it means for you
Every coverage map is a model of predicted signal outside buildings, calculated from terrain, mast locations and transmit power. It is a perfectly good first filter and a very poor conclusion.
A headline like “99% population coverage” describes people, outdoors — not land, and certainly not your kitchen. Run the network’s own checker and Ofcom’s independent one together, lean on the indoor figures, and where they disagree, test rather than guess.
The facts
- Cause
- Building materials
- Worst offenders
- Insulation, thick masonry, metallised glazing
- Free fix
- Wi-Fi Calling
- Also needed
- 4G Calling, since 3G closed
What it means for you
Modern insulation, thick stone and metallised glass all block radio. This is physics, not a fault in the service, and no amount of complaining changes it.
| Remedy | What it does |
|---|---|
| Wi-Fi Calling | Routes calls over your home broadband so walls stop mattering — free on every major network |
| 4G Calling | Required for voice now that 3G has been switched off nationally |
| Moving a metre | Toward a window changes reception measurably |
| Signal repeaters | Bought independently they can interfere with the network — ask your provider what it offers |
The facts
- Looks like
- Full bars, nothing loading
- Actually is
- Too many phones on one mast
- Worst at
- Stations, venues, city centres, early evening
- Handset fix
- None exists
What it means for you
Full signal bars with nothing loading is not weak reception at all — it is too many handsets sharing one mast. It clusters around transport hubs, venues and city centres in the early evening.
This matters because switching network cures a coverage problem but may do nothing for a congestion one. If the alternative network is equally busy at the same spot at the same hour, you will have moved for nothing.
The facts
- Method
- One rolling month on the target masts
- Duration
- An ordinary week, not a good one
- Test
- Rooms you use, at hours you use them
- Repeat
- Once a year
What it means for you
| Network you want to test | Cheapest way to test it |
|---|---|
| O2 | giffgaff or Tesco Mobile |
| Three | SMARTY or iD Mobile |
| EE | 1pMobile |
| Vodafone | VOXI or Lebara |
Live on the test SIM through a normal week — home, work, the commute, the supermarket queue — and include your commuting point at rush hour. Re-run the check once a year, because masts are built and re-tuned constantly and two national estates are currently being merged.
Still unsure after reading this?
Ring the desk and we will go through it with you. There is nothing to buy at any stage.