Self Registration
Template:HDlink allows any users who come to your portal to log in using their Facebook, Twitter, or Google ID. Self Registration is enabled when Template:HDlink.
In many cases, it makes sense to do that. For example, if a product is sold through retail channels, customers will come to the service desk through the organization's website, and register themselves to get support. In such circumstances, there is rarely a need to invite contacts to the Service Desk (although it can be done).
In other cases, access to the Service Desk is much more restricted. In a B2B setting, for example, only employees of a client company will be eligible to register as service desk users. In those circumstances, you'll want to [[Template:HelpDesk:Inviting Contacts|invite contacts]] to use the portal.