I was asked to come in on a day off unless it was already scheduled OT and I knew it was coming way ahead of time. But bff spent years as a nurse, and towards the end, yes, she turned her phone off or otherwise ignored it. IMO, you've already gone above and beyond your duty and you're under no obligation to say yes every single time they ask you to work a shift you weren't scheduled for. And honestly, if you *do* turn your phone off/ignore your phone and they call you, and you *do* get questioned or "punished" for not being there, start looking for another job.
ETA--when I was growing up, Dad worked for IBM as a repairman. He was expected to be available via the phone all hours of the day and night. Sometimes he'd take a call in the middle of the night. Sometimes he ignored it. Once, a boss yelled at him for not answering the phone the night before and wasn't placated when Dad explained he's totally deaf in one ear and had been sleeping on his good ear, thus he very literally didn't hear the phone ring. But Dad never got in any serious trouble for not taking calls when it wasn't his scheduled time to work. I always had to laugh though at some of the excuses his co-workers gave for not answering the phone/going out on a call after hours. My favorite was "my wife and I are trying to have a baby and I need to be there for the process". I also liked, in a *rme* way, the time when Dad got yelled at for not answering an after hours call, but his co-worker was excused because "it was poker night". Apparently their boss at the time was a HUGE poker fan, and poker night was apparently a super legitimate excuse not to pick up the phone 😁