I once had briefly traveled into a different time zone (so briefly that I hadn't thought about it) when I received a phone call asking to reschedule a doctor ap

I once had briefly traveled into a different time zone (so briefly that I hadn't thought about it) when I received a phone call asking to reschedule a doctor appointment. I entered the new time into my calendar. Then, I was an hour late to the appointment. My phone had adopted the timezone of the cell tower, and the calendar assumed I had meant "local time where I scheduled the appointment".