Now that I have a business of my own, the buck stops with me. I have employees, who I trust completely with my name, my brand, my clients – but that doesn't reduce the need for people to be able to contact me. In fact, when the business was just me, it was generally a lot easier to get time away, as I had fewer clients hoping for my time.
Funny thing is, I just had a conversation with one of my staff, saying "And if there are any hassles, just call me – except between 9 and 10 tomorrow morning, because I'll be presenting to the PASS AppDev Virtual Chapter. I'm doing that twice – once tonight at 9pm, and one tomorrow morning. That's 7:30am and 7:30pm if you're in the eastern parts of the USA. So clearly, 'time away' is a thing that I already do with frustrating regularity.
If you ever teach a Microsoft course, you will find a slide that recommends students turn off their phones, suggesting that they can pick up messages during breaks, etc. Except that I've generally found that if I suggest this to students, they look at me with horror, as if I don't understand the importance that they have back at their office. So I don't do that, and haven't done it for many years. Instead, I tell people that they're welcome to leave their phones on, but to bear in mind that phone-calls may bother the other students. I'm also happy to suggest to the students that if they feel incapable of leaving their responsibilities for a few days that they work on that, and find ways to avoid feeling that way.
My take is the old line "Just because you're necessary doesn't mean you're important", and I think back to times when I've known people afraid to give up their piece of knowledge, which they feel keeps them employed. In fact, this causes them to be a liability, and the company may suffer if they get sick or unavoidably detained.
The "obvious" answer to being able to get away from a job (for a holiday, training course, sickness or lunch) is automation. But I think it really comes down to doing regular handovers. If you can make sure that you're never the only person in an organisation who has the required knowledge for something, then you should always be able to get away. Similarly, you work with your colleagues to help them achieve the same. If you don't, then holidays will be ended with piles of extra work, and you'll even find yourself being on holiday with the phone ringing. Hopefully when I head over to SQLBits (to present two sessions and a precon), or to the SQLPASS Summit (to present two sessions), or to TechEd Australia (just as a delegate for the first time in five years), I won't need to be fielding calls (although I imagine that it could well be the case, because I'm describing a situation which I still haven't quite achieved, and after all, the buck does stop with me).