Ringer on iPhone does not work
Cannot here ringer on iPhone 12 Pro Max
iPhone 6, iOS 11
Question marked as
Some things to check:
The ring/silent switch on the left side of the phone. See the following Apple article: Use the side, Home, and other buttons on your iPhone - Apple Support
Check the ringer volume at Settings > Sounds & Haptics > Ringtone & Alert Volume.
Settings > Phone > Silence Unknown Callers. See: Detect and block spam phone calls - Apple Support
Do Not Disturb. See: Turn off Do Not Disturb - Apple Support
If none of the above, also try restarting. See instructions in: Restart your iPhone - Apple Support