Realme
Turn Wi-Fi Calling On or Off auf Realme
Weak indoor reception often has nothing to do with a hardware fault. It usually means the cellular signal is too weak to hold a stable call, especially in basements or buildings with thick walls.
Wi-Fi Calling solves this by sending voice calls over your Wi-Fi connection instead of the mobile network. Your carrier still has to support the feature, otherwise the toggle stays inactive or calls fall back to the regular network automatically.
On Realme UI you manage this setting under mobile data options. Go to Settings ➔ SIM card & mobile data, then pick the SIM you want to configure if you use dual SIM. Tap Wi-Fi Calling and enable or disable it from there.
After enabling it, open the same menu again and set your Wi-Fi Calling Preferences. This decides whether the phone prefers Wi-Fi over cellular or only switches to Wi-Fi when the mobile signal drops.
If your carrier does not support Wi-Fi Calling, the option may be greyed out or missing entirely, and enabling airplane mode plus Wi-Fi manually will not replace it. In that case, check with your provider before assuming the phone is at fault.