These "symptoms" describe a phone that is in airplane mode. Dialing *228 on some cell networks may improve reception, but it will not address issues with WiFi or bluetooth. The same can be said about using the phone outdoors. These symptoms do not describe an overheating phone.
Airplane mode, aeroplane mode, flight mode, offline mode, or standalone mode is a setting available on many smartphones, portable computers, and other electronic devices that, when activated, suspends radio-frequency signal transmission by the device, thereby disabling Bluetooth, telephony, and Wi-Fi. GPS may or may not be disabled, because it does not involve transmitting radio waves.
The name comes from the prohibition by many airlines of using equipment transmitting radio-frequency signal while in flight; using airplane mode …