When a new user is added to the Grasshopper account, they are given the ability to log in to the online portal with their own unique username and password. The features and settings they have access to will very depending on the permissions they are given

TIP: Keep in mind that an individual doesn't need to be a user in the online portal in order to receive phone calls or use the Grasshopper apps. How calls are routed and received within Grasshopper is determined by your call-forwarding settings, not user status. 

User Type Permissions
All users
Users with extension access