storing a table of special identifications, wherein the table of special identifications is valid for a group of subscribers in a closed user group of a communication system, the closed user group comprising a plurality of subscribers, the special identifications corresponding to entities outside the closed user group with whom connection access is allowed;

receiving a request for a connection between a first entity and a second entity, the first entity being one of the group of subscribers of the closed user group;

a) checking whether the connection is within the closed user group;

b) checking whether the connection is allowed if it crosses the border of the closed user group;

c) checking whether the second entity corresponds to the table of special identifications listing entities outside the closed user group with whom connection access is allowed; and

giving connection access if at least one of the conditions a, b and c is true; and

rejecting connection access if each of conditions a, b and c is false.