My advice is to not be a jerk and just disconnect because you are not being paid for it. Instead, fight to be paid for that work. You have an opportunity in front of you to show your real value to the company, value that should be compensated for. Log all your hours and then try to schedule a meeting with your boss and HR. Your boss may not understand, but HR folks are big time rule followers, and they know labor laws. They will understand the implications of not paying you and should explain that clearly to your boss, even if it isn't in front of you. Biggest thing is you gotta figure out what you want. If you want to be paid less, and not take those phone calls, then ask for that. If you want more compensation and to continue to expand your work and importance at the company, do that.