There are two status possibilities for calendar entries at the moment:
not available (standard) and "mark as available".
These control the free time of a person, so that other people can see, if the person is avaible for a meeting or not.
It would be great to have a third possibility: "Home-Office".
Other people could see, that the person is available, but only reachable via phone or video conferencing. The person is not physically available.