Notification That a Contact is Using My Phone

Leave it to my father to get the craziest of problems. Recently he's had a notification appear on his Mac saying a contact is using his phone. I'm not sure if it's the same contact every time or not as I was just told about it. There's no way to dismiss the window either. Clicking "End" does nothing. He told me he did call the contact pictured this morning using his iPhone so I'm sure that's the reason. But this is a very new thing and I'm not getting the same notifications when I use my iPhone.