There's a gap right after 'how are you, I'm fine, how are you' — a few seconds where the call could go somewhere real, and it almost never does. You ask about the weather. They ask if you've eaten. Both of you know there's a longer conversation sitting right there, and both of you let it pass, because it's easier to hang up light than to hang up honest.
What's actually in that gap for you? Maybe it's 'I'm not doing as well as I said.' Maybe it's 'thank you for the things I was too young to say thank you for.' Maybe it's just 'I miss how things used to be, before we both got so careful with each other.'
You don't have to call right now. But sit with what you'd say if you did — because one day the phone will ring on the other end and nobody will pick up, and the thing you kept meaning to say will still be exactly that: meant, and never said.