Look at the situation
A coverage prediction is a model rather than an inspection of your room. Check indoor and outdoor predictions at home, work and the places used regularly. Ofcom and provider maps can help compare, while a provider status page shows current disruption.
Read the conditions
Building materials, a basement, busy-time demand and handset support affect experience. Record voice calls and data separately. Comparing only one speed result does not explain the whole service.
Choose the next question
Ask whether the exact handset supports the provider’s present calling technologies. Wi-Fi calling is a device-and-account question; it is not guaranteed by the existence of home Wi-Fi.
Keep official confirmation in view.
All explanations here are general guidance. Use your provider’s current instructions and service documents before taking action.
Official reading routes