Love the line about calling. People in this thread dont get it - if you're going to triage me against your other priorities, and if you dont care enough about our friendship to try to pickup when I call - you're not really a friend. We can still be friendly, but you're too self obsessed and 'busy' (in the inorganic, modern sense) to really be a friend
When I'm very busy or focused, and then a friend calls, I don't want to sound short and perturbed, and I don't want to answer just to plead "I'm too busy right now". This is what voicemail is for, and so long as the call is responded to in relatively short time then no foul has occurred.
I'd be leery of "friends" who want attention and interaction on demand. Only my wife has that right.
'try to pickup' - totally hear you on the voicemail thing. If you're consistently too busy to take any calls from any social contacts, you're too busy to have a deep friendship anyway. We can still be friends, but never having real substantial conversations is going to he a limiting factor on how deep that goes.
If you're married, of course you should prioritize your immediate family - a lot of people get more distance on existing social relationships or lose track of friends at that stage of life for that reason. It's not really a bad thing, it is what it is - the loss of an active friendship.