Map the places that matter
Start with home, work and the journey between them. Check indoor and outdoor predictions separately using the provider tool and Ofcom’s coverage resources. Population coverage is not a measure of every square mile, and a 5G symbol is not a speed guarantee.
Separate four different symptoms
No service, calls failing, slow data and intermittent indoor reception can have different causes. Note the place, time, handset and whether other people nearby are affected. A temporary outage should be checked before changing settings.
Try proportionate checks
Restart once, check flight mode and the selected SIM, and install supported software updates. Test outdoors if safe. Do not reset or delete an eSIM as a first step: you may need provider verification to restore access.
Decide with local evidence
Compare the same locations and similar times. If one provider performs poorly indoors, ask about Wi-Fi calling compatibility, but remember that it depends on suitable Wi-Fi and device support.
Take the next step carefully
This is general information, not account-specific advice. Check the official provider before changing service. For consumer switching and contract information, consult Ofcom’s switching guidance and contract change guidance.