Phone not ringing when number not in contacts

Have you checked Settings?

Settings/Apps/Phone/Silence Unknown Callers

If that's on, switch it off. I have it on because I'm plagued with spam phone calls at the moment (and OfCom, the UK regulator, seems unable or unwilling to do anything about it).

Rustychris Said:

"Phone not ringing when number not in contacts: Phone going straight to message bonk of number not in my contacts"

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Troubleshooting Calls Going Strait to Voicemail:

A. Create a Contact of this Number:

If you are not getting a call, then add this number as a contact and then see if you get is caller.

If no success..

B. Go here: If your Call Fails or you can’t Receive Calls on your iPhone - Apple Support