At my work I was told it was viewed as if they would be able to walk up to my desk to ask me stuff if i were in the building. Which even then, expecting someone to drop everything they're doing to talk to you is kind of shitty if they are demonstrably busy.

Though that wasn't the problem I actually had, my problem was that they kept doing so when I was not on call, not working, and trying to sleep, in order to ask some inane question they could ask anyone else working, but she kept doing it to everyone as a power trip thing, as she would threaten to write you up if you failed to answer. After three calls during the same night I checked with the union rep, who then went ballistic at several people and she was quietly reassigned to a different hospital, which led to much rejoicing among me and my colleagues