If you are asking this question, my guess is that you're a covert stutterer. You have the ability of hiding your stutter not only to your collections but also to your boss. Many people will see this practice as the ideal thing but if I were you I will shun covert stuttering and open up to the people I work with.
When you hide your stuttering you only make yourself live a caged life which will constantly torment your spirit because your mind can never be at rest. Your mind will never be at rest because it knows too well that there will be a time to pass memos to a fellow college, a time to speak on the phone, a time to lead a seminar, a time to answer questions either from your collections or your boss. The point is that your daily life both in the office and at home requires a minimum amount of speaking, which means it will not take time before your stuttering will be noticed; the implication is that if they notice it themselves it will be hard and too late for you to gather yourself.
Secondly, hiding your stuttering makes your colleagues and employer see you as a fluent and smart employee and with this belief, much expectation will be delegated at you which automatically makes you a target or figure to always remember when issues are discussed. Your boss will not have to think before he sends you to represent him in a meeting or cover for your colleague who is on leave. The implication of this is that you will likely lose the control you have over your covert stuttering because you have been noticed and placed at a point where you need to learn new things before you can stand, learning these new things will require you to ask questions or report periodically to your boss who most times will subject you to a hurried condition expecting you to tender your report in a few seconds. On the other hand, when you let yourself open, your boss and colleagues will learn to work with you the way you are, it increasing your chances of building and positioning yourself for good.
Finally, covering your stuttering will help to build a mountain of low self-esteem in you. One thing about stuttering is that the more you hide it the more different it becomes; it requires you to let go of your shame and fear; which means you need to be as open as a hollow object to grow your confidence level. You are much more confident with what you have known and accepted than the one you shy away from.