Modern phones don't constantly search for a better signal to save battery life, so the user needs to take some steps to improve their connection.
The quickest solution is to turn on airplane mode («airplane mode») for 10 seconds and then turn it off.
After that, the phone automatically starts searching for available networks. On iPhone, this feature is available in Control Center, and on Android – in the Quick Settings panel.
Sometimes you need to restart your phone, especially if you've crossed an international border or are in a roaming area.
Don't forget to check for software updates on your device. Manufacturers often fix connectivity issues in new software releases, so keep an eye out for update notifications.
If your SIM card has been used for a long time, it may wear out, lose contact, or not support modern network frequencies. Start by removing the card and gently wiping the metal contacts. If that doesn't work, contact your carrier to replace your SIM card with a new one while keeping your number.
4G and 5G networks operate at different frequencies and from different towers. Sometimes your phone will try to connect to a weak 5G signal instead of a more stable 4G signal.
To fix this, on your iPhone, go to «Settings» » «Cellular» » «Voice & Data» and select LTE (4G) or automatic mode. On Android, the setting is made through «Connections» » «Network & Internet» » «Mobile Network».
Modern phones allow you to make calls over Wi-Fi. To activate this feature, open the cellular settings and turn on the corresponding option. This is especially useful at home or in the office where the mobile connection is unstable.