There is a tremendously valuable asset going to waste in your organization - face time. Face time is that old real estate principle of highest and best use applied to the boss. More about these in a moment. Office time rarely has the same value as face time.
Offices are too often a place to hide.
If the boss really has superior expertise. If the boss is only marginal, then maybe the office is the place where he or she is least likely to do damage. Otherwise, most of what gets done in offices either could be done by someone who has a much lower face value or, as is often the case, work that really needn't be done at all. Pagers are a variation on the theme. Pagers are too often an excuse to be someplace you shouldn't be.