You have a Skype for Business Server 2015 infrastructure that has Enterprise Voice enabled. When a caller dials an unassigned number, the caller hears a custom message, and then the caller is forwarded to a user named User1. Several months later, User1 leaves the company. You need to ensure that when a caller dials an unassigned number, the caller hears the custom message and is forwarded to a user named User2. Which Skype for Business Management Shell cmdlet should you run?