Iphone 8 keeps blocking contacts

Hello jwwindle,

Welcome to Apple Support Communities. We'd be happy to work on this issue with your father-in-law's iPhone and Contacts. You've already worked through several steps we would have recommended like updating his iOS version and contacting his carrier.

Have you also had him try to completely remove a contact then re-add it as a new one? The goal will be to see if the new contact card (without it having been blocked before) will resolve the issue.

Open Contacts. Scroll to the Contact card you want to test. Tap on it, then Edit (top right of the display). Scroll to very bottom and tap 'Delete Contact'.

Restart his iPhone. Now, time to add the same number back.

Open Contacts.

Tap +.

Enter basic information for the contact, then tap Done.

Restart his iPhone again, then have him test that contact. Response back with how it goes.

Warm regards.