Users have a primary extension and can have up to 9 other alternate extensions suffixed with a letter. For example, User 1000 may have a primary extension of '1000' but can also have extensions such as '1000a', '1000b', and '1000c.'Some extension suffixes are reserved for various systems' usage. This article is to track extension suffixes that we recommend NOT deploying.suffixUse case (reserved for)mReachUCtMicrosoft Teams integration