Technical information

Tools that Restrict Unauthorized Outgoing Calls
Issue 7 June 2001
4-13
Class of Restriction
For DEFINITY ECS, DEFINITY G1, G3, and System 75, the Class of Restriction
(COR) places calling permissions and restrictions on both the calling party and the
called extension. Up to 64 CORs can be defined in the system. For DEFINITY
ECS, DEFINITY G3rV1, G3i-Global, and G3V2, the number of CORs has been
increased to 96. For DEFINITY ECS and DEFINITY G3V3, each COR may be
assigned a unique name via the Class of Restriction Form. CORs are assigned to
trunks, stations, authorization codes, attendant consoles (as a group), remote
access barrier codes, and loudspeaker paging access zones. CORs provide or
prevent the ability to make specific types of calls or calls to trunks and stations
with other specified CORs.
You can use the COR calling permissions (COR-to-COR restrictions) that set
calling permissions on the COR to disallow stations to access trunks, and to
disallow trunk groups to access other trunk groups. The COR also assigns Facility
Restriction Levels (FRLs) for use by WCR/AAR/ARS routing.
NOTE:
When a call is routed to a VDN, the COR of the VDN determines where the
call can be routed. If the COR is not restricted and the vector contains a
collect digit step, the caller could dial 9 or a TAC and be routed out of the
system to the network.
For DEFINITY G3 systems prior to DEFINITY ECS Release 5, as well as for G1
and System 75 systems, the default value of the “FRL” field on the COR form is 7.
Starting with DEFINITY ECS Release 5, the default value of the field is 0. This is
true for all CORs except for CORs 10 through 17, whose defaults are 0 through 7,
respectively. These defaults help ensure that FRLs with greater calling privileges
are assigned only when appropriate.
To help maximize system security, follow these steps:
 Assign a separate COR to incoming and outgoing trunk groups, and then
restrict calling between the two groups.
 Limit the calling permissions as much as possible by setting appropriate
Calling Party Restrictions and FRLs.
 Restrict the port COR of adjuncts from accessing the trunk group CORs.