Hi @rajomay, let me see if I can help out here!
First of all, have you checked whether the Do Not Disturb-mode is activated on your phone or not? DND is a mode that prevents the phone from notifying for incoming calls and notifications. To check this, drag the status bar fully downwards using two fingers to access the Quick settings panel, tap the DND-icon, if it is on, tap the slider to turn it off.
Another thing that you can try is to clear all data for the phone app. This will reset all settings for the app which might do the trick. Find and tap Settings > Apps > Phone > Storage > Clear data > Tap "OK" > Restart the phone.
Try these measures and let me know how it goes!
