Maryelizabethrose - as others have said, you just have to follow parent's wishes. However, in the meantime, rather than trying to communicate by phone, which seems to be a problem, ask your son to send photos and short videos.
Having a son and family living in a different country, I found short video clips much better than trying to have a video call. I could watch the videos again and again, if I wanted, whereas with live calls, children were cranky or crying often!
Mortgage at 72 - is this possible?
paying a teenager for watering