Closed subscriber group

A closed subscriber group is a limited set of users with connectivity access to a femtocell. When a femtocell is configured in CSG mode, only those users included in the femtocell's access control list are allowed to use the femtocell resources.
On the other hand, a femtocell can be also configured in Open Access mode, in which any user is allowed access to the femtocell.
A closed access femto will accept LAU only from a subscriber who is in the ACL of the femto, the other subscriber, named as Public User, who is not in the ACL will get a reject with a roaming not allowed cause 13 or 15.