Making phone calls "unnannounced" has always been a struggle of mine, mainly because I start to think "am I bothering them?" and then negative thoughts start to flood in. I do have anxiety issues which I go to therapy for, but I'd put making phonecalls lower down the priority list of things to tackle because it's not that important to me in the grand scheme of things.

Completely irrational, I know, but that's where I'm at. Usually if I want to make a phonecall I arrange it with the person for a set time that suits both parties.