I'm right-handed, but for decades have used the phone in my left hand -- I found this to be useful at an early job that often required taking notes whilst on th

I'm right-handed, but for decades have used the phone in my left hand -- I found this to be useful at an early job that often required taking notes whilst on the phone, so I optimised behaviour for that and the habit stuck. When early cellphones came along I had no trouble using my left hand only when most "right-ies" I know used them with the right hand. Since smartphones became popular I still phone with my left hand primarily, though I have become more ambidextrous with it, and I've noticed that others seem to switch hands more too.