Calls from my iPhoneX are being rejected by my husband's LG Exalt phone.

[Conchalaw]

We use these 2 phones for work purposes and call each other multiple times a day for years and years. For around 2 weeks or so all my calls are "rejected" according to the message on his phone. He receives calls from any other number, and I can call any other number with no problem. I can text him, but not call him. He can call me but my calls are rejected and dont show up on his recent calls list, NOR is my number blocked on his phone.  HELP!