MERLIN LEGEND Communications System Release 6.1 | Issue 1 |
Network Reference 555-661-150 | August 1998 |
4 Security | |
Facility Restriction Levels and Remote Access | Page 4-5 |
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!SECURITYlALERT:
Networked systems require special attention to security issues. Follow the rules below when setting up and planning your system for network use.
■Ensure that barrier codes are required for incoming remote access calls received on PSTN dial-plan routed facilities and tandem facilities that route to the local system by dialing the Remote Access code (889, for example). When you program the default COR, turn the barrier code requirement on. This setting is ignored for ARS calls and calls to non-local extensions across the network. However, it is still applied to DID and PRI dial-plan routed remote access calls as well as to calls received on a tandem trunk and routed to a Remote Access code. Because the COR Calling Restriction must be set to unrestricted for network calling, using barrier codes on these facilities is essential in order to apply security measures. When a Remote Access code is included in the non-local dial plan of the calling system, the caller must enter a barrier code and that barrier code FRL on the called system is compared to the UDP or ARS route FRL on the called system. See the Feature Reference and “Remote Access Default Class-of-Restriction Settings” on page 6 for details.
■Extension and ARS FRLs should be carefully and stringently assigned in order to prevent unauthorized trunk-to-trunk transfers to local PSTN facilities. Table 4–1, page 4-3 explains the operation of this feature in a networked system.
Facility Restriction Levels and | 4 |
Remote Access |
Facility Restrictions Levels (FRLs) are number values from 0 to 6 that are used to allow or disallow calling. FRLs apply to the following four aspects of systems in a network:
■Automatic Route Selection Routes. ARS routes are assigned to subpatterns that the system selects according to the time of day. Each route is assigned an FRL. An FRL of 6 is the most restrictive, and an FRL of 0 is the least restrictive. Factory-set ARS route FRLs are as follows:
—Routes assigned to Default Toll Tables: 3
—Routes assigned to the Default Local Table: 2
—Routes assigned to pools: 3
■Uniform Dial Plan Routes. UDP routes are associated with patterns that also specify digit manipulation for directing calls to non-local extensions over tandem facilities, or directing calls to non-local PSTN facilities. Like ARS routes, UDP routes are assigned FRLs. The factory setting for UDP routes is 3.
