Solutions are displayed which match your selected specification «No ringing from calls (phone)».
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Disable the airplane mode
Maybe your device doesn't ring because of the Airplane mode. If you don't see the signal strength, nor the operator's name in the upper-left corner of the screen, but you see a small airplane icon, the airplane mode is enabled.
If your iPhone doesn't ring, but you receive notifications in your voicemail that somebody called you, it's possible that you have enabled the Do Not Disturb option. If you see a half-moon icon next to the battery icon, this option is enabled.
You can disable this option via the Action Center or via Settings:
Via the Action Center:
Swipe up from the lower part of the screen and tap the half-moon icon.
Go to Settings -> Tap Do Not Disturb -> Move the switch next to Manual to the left.
The call diverting feature enables you to divert all the incoming calls from one phone number to another. If you have enabled this feature, you won't be able to receive calls; therefore, your device won't ring.
Go to the device's Call Settings and disable call diverting. If you are not sure how, ask the carrier (operator) you are subscribed to for instructions.