I think the problem is that there's a perception that a phone call is an interrupt event. Because you have a person on the phone waiting for you to answer, you have to (or should) answer the call.
So, if the matter is important then a phone call is completely appropriate. But if it's just a call to say "hey, how's it going?" then perhaps a text message or email is a better choice with a "let me know when it's a good time to call" added in so you can have a normal voice conversation without either party being interrupted.
So, if the matter is important then a phone call is completely appropriate. But if it's just a call to say "hey, how's it going?" then perhaps a text message or email is a better choice with a "let me know when it's a good time to call" added in so you can have a normal voice conversation without either party being interrupted.