They think that because you work from home, you don't work. If they bother you and you tell them "I am working" they think you are blowing them off "Oh you can do that anytime you want". No. It is a Job, a business. I work just like you and twice as hard sometimes. When I am working, I am working.
Treat it the same as if I bothered you while you were sittign in your cubicle.
