My dh is a doctor - a GP.
He calls me at lunchtime - by then he can often tell just how late he's going to be.
In an emergency I call his reception desk and they get him when he's between patients.
Then he usually phones on his way home because he mistakenly thinks I might have dinner ready
We probably talk twice a day, and I realise that's quite a lot for most couples.
Our school insists that there is an "alternative contact" - not the parents! - for each child. Most folks use grandparents/aunties but we have none close, so a good friend does it for us.
So on the one occasion I had to pick up a child and go to A&E, I called the friend and he happily picked the others up, and I let dh know. He works 75 mins away, so wasn't able to pick up anyway.
I think if you have a spouse/partner who isn't contactable, it's only common sense to have a network. When I broke my leg my neighbour took my dc in after school, fed them, looked after them until dh got home. We look after her lizard thing when they're away. I've a list of at least 5 folk I can call on in an emergency. There are times you need your family (and my dad has driven 2 hours, my mil got on a plane) in emergencies, but a realistic back up should be achievable).