Instruction manual

Tools that restrict unauthorized outgoing calls
Issue 9 May 2003
5-15
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 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 screen 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.
Calling party and called party restrictions
For DEFINITY G3 systems prior to DEFINITY ECS Release 5, as well as for G1
and System 75 systems, the default value of the
Calling Party
Restriction
field on the COR screen is none. Starting with DEFINITY ECS
Release 5, the default value of the field is
outward. This default ensures that the
ability to place calls that access public network facilities is assigned only when
appropriate.
The following restrictions can be placed on the originating station or trunk:
■ Outward Restricted: cannot make public network calls via AAR/ARS or
TACs. Calls can be placed to internal stations, to tie trunks via TACs, and
off-switch via the Uniform Dial Plan (UDP).
NOTE:
Some states require that all telephones be able to dial emergency
numbers, such as 911.