- Check the signal strength on the phone screen. To increase signal strength, move your phone slightly, or if you are calling from inside a building move closer to a window.
- Set your phone to use GSM (2G) network only: Select Settings > Phone > Network mode > GSM in case the roaming operator does not permit you to use 3G service (not available on some phones).
- Check that your phone is not in offline or flight mode: Select Settings > Profiles.
- Restart your phone and make the call again.
If you continuously experience low signal strength in a certain area, it may be that network coverage is insufficient there. For more info, contact your network service provider.