1. Check the signal strength on the phone screen. To increase signal strength, move around, or if you are calling from inside a building move closer to a window.
  2. Try reconnecting by switching Flight modeOn and back Off in Settings. This resets the active connection.
  3. Check the settings of your active profile, especially ringtone, and ringing volume. Select Settings > Sounds and vibra.
  4. Make sure that call forwarding is not switched on: Select Settings > Calls > Call forwarding.

If the problem persists, remove the battery, replace it, and switch your phone on.