Let them wait
The problem: A lot of people come to ask you although not necessary.
A problem that usually only a few people in a company have – but these few know it very well: They are known to have good knowledge in a lot of areas or have good knowledge about the company and it’s organization or environment. And so they get asked often and therefore get interrupted very often in their main work.
What often surprises most is that a lot of answers could have been easily found online (Google, Wikipedia, company intranet sites, e-mail in-boxes or archives and so on).
The reason: You are the most efficient way to solve their problems.
When they look up the information somewhere else they have to think more and it takes longer. And maybe they at first have to think first where to look up (first). As they usually know already your phone extension or have their chair next to you it is the easiest, fastest, most efficient – and maybe also most reliable way to ask you.
Although this might be part of your daily job and might be a good motivation being such an esteemed person it may grow to a level where you cannot do your main job efficiently because you have too many other “little problems” to solve or “little questions” to answer.
The solution: Let them wait.
If you let them wait a little for answers you are not the most efficient way for those little questions and problems that interrupt you more often. When they have to wait they will maybe “in the meantime” get an idea where to look up the information themselves getting there solution faster. – And the problem get solved without you.
If there are questions coming often not so easy to look up for them then write a documentation and publish it (on the internet or intranet or some wherever your company usually stores such information). When these questions come again you simply tell them to look it up. If your standard answer is “Look it up in our repository” it is even less attractive for them to call you because they could have looked up immediately without calling you.