Closed User Group

Closed User Groups are groups of GSM mobile telephone subscribers who can only make calls and receive calls from members within the group. This service is not usable with the short messaging service (SMS) system.

A subscriber may:

If the user is a member of multiple Closed User Groups there will be a Preferred CUG assigned by the network that will be used by default. However, it is possible on a per-call basis to specify a different Closed User Group (of which the user is a member) for the call. It is also possible on a per-call basis to suppress the use of the Preferred CUG i.e. act as if the user is not a member of the Closed User Group, and to suppress the Outgoing Access permission i.e. to insist that the call only go through if the destination is a member of the CUG.