My dc all talk to their dad each day on the phone.
In our case, it was set up long before we separated, due to exH’s long working hours (great dad, huh?), so they at least had some daily contact with him - he was out of the house before they got up, and back long after their bedtime.
So, now we are separated, the daily phone call continues.
Yes, he uses it as a way to bugger about. Not fixing a time (he is just far too busy and important), not always calling at a convenient time, etc. But overall, it’s a time for the dc to speak to him, if they want to. Eldest does, at length. Middle one does if the want something specific, but otherwise hates talking on the phone. Youngest mostly just says ‘hi, I’m busy, see you soon’. But it’s in their control.
He calls my phone, not the dc’s phones, although this may change as they get older (although I’m sure they’ll then often ignore the call, tbh)
I don’t always call the dc when they are with their dad, but I do if I haven’t seen them that day(so if they are staying more than one night) . I wouldn’t like to not have daily contact (or potential for contact) with them, it’s nice to just touch base, and I don’t see why he would feel any differently about this. Most importantly, I don’t wan the dc to think he feels any differently about this, and so for now, it works to their benefit.