CUG Full Form is Closed User Group. These are groups of GSM (mobile phone) subscribers who are allowed to receive and make calls within members of a group. However, CUG does not include SMS service. There are certain rules that apply to the CUG members or subscribers.
Some of the dos and don’ts of a subscriber are: (1). He can be a CUG member of up to maximum 10 groups (2). He can have outgoing access and makes calls outside the group (3). He can receive calls from outside the group (4). He can make emergency calls. However, this supplementary service is limited to organizations and is not applicable for the public. Most of the modern handsets include CUG service applications.