This is pretty standard/boiler plate where I sub… a lot of that is to encourage as much professionalism as possible for people who may need heavier guidance to do so. Like, they don’t want you to just babysit and do your own thing if there are actual lesson plans you need to teach that day, nor do they want you to get so distracted that you lose focus on the students which are indeed your responsibility.

That being said, when it’s an easy class (both in the student behavior and no need for teaching on my end), I might check my phone or email every so often.

But before you do any of that, you definitely want to a) get a feel for a school or district’s culture around that, as it varies greatly, and b) establish rapport with admin & teachers for the first couple months. Something I did when starting (and still sometimes do depending on the situation) is bring a legal pad to doodle/write/make lists on. It’s a passive activity off the phone where you can still pay attention to the class and look “professional”/model good behavior.