It's a difficult problem with grown up adult children.
You can't insist they ring you, just hope when you say how much you miss them and you would really like a phone call at least once a week they would comply but there's no guarantee.
I guess I'm lucky my son FaceTimes very regularly for us to see the grandchildren.
Daughter tends to phone at least once a week and messages and sends photos of the grandchildren regularly.
But then our children don't live nearby so we don't get to see them on a regular basis.