•
Silence ringtones during hours you specify. Use Do Not Disturb.
•
Choose a unique ringtone for specific people. You'll know instantly who's calling.
•
Get notified of incoming calls when you're on a call. Set up call waiting.
•
Set the number of rings before sending a call to voicemail. Dial into voicemail, then follow your 
carrier’s prompts to change this setting.
Fix an issue
If your phone isn't ringing for incoming calls, look for   in your status bar. Open quick settings and turn 
 Do Not Disturb off. Your phone will ring for incoming calls. Check your settings to make sure your phone 
is screening calls at the appropriate times.
If you’re having other issues, try these troubleshooting steps.
Contacts, calls, voicemail : Phone calls 137