DH has to file a report with work every Sunday, even if he only works one day of the previous week. Since we usually travel mid week to mid week, I know that he has to at least do that when we are away. He brings his work laptop and checks his email once a day unless something is going on that he needs to be more involved in.
And chances are, he will have to take at least a couple of calls. It gets a little gray though since he's friends with some of the people he works with so the calls will often be one quick question and then friendly conversation. I don't mind if it's fairly short, but if he gets over 10 minutes, you can feel the waves of frustration coming off me. Then I start muttering, not too quietly, "You hang up first!" "No you hang up!" "Okay, I'm really hanging up now." "Okay, on the count of three, lets hang up together." "You didn't hang up!" That usually gets him off the phone pretty quick.
Oh, and if we are gone at the end of a pay period, he has to submit his time sheet. He tries to get that done as much as he can before we leave, but he has to code each and every 15 minutes based on what he was actually doing so if he takes calls while away, he has to account for those. I fully support his doing this though, since he doesn't get paid if he doesn't do it. I like when he gets paid.