Compare every network at the full postcode, then verify the strongest candidates with a real phone indoors.
Step 1: compare predicted coverage
Use Ofcom’s Map Your Mobile checker rather than relying on one provider’s marketing page. Enter the full postcode and compare predicted indoor and outdoor 4G and 5G coverage. Treat “variable” as a warning to test, not as a promise of reliable service.
Step 2: check the operator’s live information
Open the shortlisted network’s own checker and status page. A long-term coverage gap and a temporary fault require different decisions. Record the date because planned work and outages can change the result.
Step 3: test the exact places that matter
- The room where you normally make calls.
- The desk used for home working.
- Bedrooms, basement rooms and internal corridors.
- The garden, driveway or building entrance.
- Any room used by a medical, security or connected device.
Make an ordinary call, send a text and load a small webpage. Test with Wi‑Fi switched off so that the result reflects the mobile network. Repeat at a busy evening time if reliable data matters.
Step 4: check fallbacks before switching
Confirm Wi‑Fi Calling support for the exact handset and tariff. If two networks perform differently, a Dual-SIM arrangement can provide useful resilience, but it is not a substitute for an emergency plan.
Compare like with like
Use the same handset where possible when comparing SIMs, because antenna design and supported bands can change the outcome. If two people report different results, note their phone models and whether Wi‑Fi Calling was active. For an MVNO, remember that radio coverage may follow the host network while calling features, traffic management and support arrangements can still differ.
Combine postcode prediction with an address trial
Start with Ofcom and the operator postcode checker, then validate the prediction using a low-commitment SIM at the exact property. Include the entrance, main rooms and any garden or workspace that matters.
- Keep screenshots of the predicted result.
- Record indoor and outdoor performance separately.
- Complete the trial within the provider’s cancellation or return window.
Official sources
Facts checked: 25 July 2026. Network features, device menus and coverage can change. Recheck your exact phone model, software version, network and plan before relying on a feature.
