- Make sure your phone's profile is not set to silent, beep, or any other profile where alert tones are silenced.
- Use the volume up and volume down keys to adjust the loudness of the alert tones.
- Change a different alert tone (Settings > Sounds and vibra > Alert tones). This is to check if the issue is with a specific tone.
- Make sure that call forwarding is not switched on (Settings > Calls > Call forwarding).
If the problem persists, remove the battery, and put it back into the phone. Switch your phone on.