Unable to Text Call One Person

Hello, I have a strange one for you.

iPhone 7 plus

iOS 12

I can call and text anyone, but one specific person.

He can text and call me and it works fine. When I text, it shows delivered but never gets to him.

When I call it goes straight to voicemail and he never gets voicemail.

He has iPhone XS.

I have tried rebooting the phone, both standard and forced.

I have reset all the network settings on my phone.

I deleted his contact and created new one from a text from him.

Any thoughts?

Thanks!