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MERLIN LEGEND Communications System Release 6.1
Network Reference
555-661-150
Issue 1
August 1998
Call-Handling Scenarios
Page 2-13Networking Guidelines
2
■ UDP routing applies FRLs to calls over specific routes for pools of tandem
trunks. A different set of FRLs is programmed for ARS routes. However, an
extension’s FRL applies to
both
UDP routes and ARS routes. An
extension’s FRL is applied only to local tandem and PSTN calls and is not
carried across the private network when the caller uses ARS to direct a call
to PSTN facilities on another switch. As you read the scenarios in this
chapter, pay attention to the following rules:
— Within a system, ARS FRL restrictions compare the local extension FRL
to the route FRL. To use a route for a call, the extension FRL must be
equal to or greater than the route FRL.
— For intersystem calling, the system compares the local extension FRL to
the UDP route FRL. To use a route for a call, the extension FRL must be
equal to or greater than the UDP route FRL.
— When a Remote Access code is included in the non-local dial plan of the
calling system, the caller’s barrier code FRL on the called system is
compared to the UDP or ARS route FRL on the called system.
— When a UDP or ARS call is routed into a system over tandem trunks and
then out of it again, the FRL assigned to the default COR for all-tie or all
non-tie trunks is compared to the FRL assigned to the outgoing UDP or
ARS route on the called system. The default COR’s FRL must be
greater than or equal to the FRL of the outgoing route on the called
system.
— When a PRI dial-plan routed or DID call is routed across systems in a
private network, the system receiving the call from the PSTN searches
the local dial plan and then the non-local dial plan for the destination
extension number. If the number is in the non-local dial plan, the call is
routed out using the UDP routing pattern for the specified extension
range. For a call to be routed out of the
next
receiving system, that
system’s COR FRL must be equal to or greater than the UDP route FRL.
— In Release 6.1 and later, when an integrated VMI calling group is used
for routing calls to a centralized VMS/AA, assign an FRL of 0 to the UDP
route for the VMI conversion number. The pattern for the VMI
conversion number should not be used for any other routing.
SECURITYlALERT:
!
Networked systems require special attention to security issues. Follow the
rules below when setting up and planning your system for private network
use.
■
Ensure that barrier codes are required for incoming remote access
calls received on PSTN dial-plan routed and tandem facilities that
route to 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 private network. However, it is still applied to DID and
PRI dial-plan routed remote access calls as well as to calls received