Nobody is allowed to call me for work on our home number. So if you can afford it, a separate phone line and a separate room are the best start. Also, if you have kids, you need to teach them that there are certain times when they're just not permitted to bother Mom and Dad. I'm able to have lunch with my wife and our little girls each day. But when Dad's on the telephone, the kids know they aren't allowed to visit me in my office.
Some people leap.
Some people get pushed. The folks who got pushed, well, they got pushed. They were forced into this way of working when they were laid off or downsized. There all kinds of such groups. BUt these groups serve a vital purpose for free agents and home-based workers.