I've made it exceptionally clear that I am not available 24x7. If my boss would like me to be on call for some period, I'm willing to discuss that, but it needs to be arranged in advance for a clear time period.
If some communication is coming in for work right now, I don't even know about it and I'll handle it on Tuesday, given the 3-day weekend. Weekends are not "extra work days", they are my time to relax, unwind, and come back to the office ready to do a much better job than if I were constantly tired, fatigued, and burnt out. Ultimately, that benefits my employer, too.