Automatic Route Selection (Ars) - Lucent Technologies MERLIN LEGEND Release 6.0 Network Reference Manual

MERLIN LEGEND Communications System Release 6.0
Network Reference 555-660-150
3 Feature Interactions

Automatic Route Selection (ARS)

Automatic Route Selection (ARS)
To help prevent toll fraud, ARS access codes for other networked systems must
not be assigned to the non-local dial plan; the local ARS access code cannot be
assigned to the non-local dial plan. For example, if the ARS access code is 9,
extension ranges such as 9000–9039 cannot be assigned. It is recommended that
the ARS access code be the same for all systems in a network.
For ARS calls over another system's PSTN lines/trunks, the system manager
programs ARS to prepend the non-local ARS access code and send it over
private network trunks to the non-local system (the ARS code is accepted over
tandem facilities, but not on incoming calls over PSTN trunks). Depending on how
ARS is programmed at the non-local system, calls may be sent to yet another
network system before they are sent out over the PSTN.
In a network, system managers program ARS to direct calls over the most cost-
effective routes in the whole network. For example, calls that are in the local
calling area or area code of a non-local system can be sent out from PSTN
lines/trunks connected to that system. At the non-local system, Remote Access
operation is used to accept or reject such a call (see
3–14 for more information) for routing to the PSTN.
The Special Numbers Table, Dial 0 Table, Default Local Table, and the Default Toll
Table need to be programmed to prepend the remote systems ARS code. In
networked systems, when the main pool contains tandem trunks, the local system
automatically prepends its own ARS access code before sending 10xxx or
101xxxx equal-access Interexchange (IXC) calls across the network. In this case,
the local and remote system ARS access codes must match for proper routing to
PSTN trunks connected to the remote system.
!
Extension Facility Restriction Levels (FRLs) are applied only to calls while they
are on the local system, and are compared both to UDP routes and to ARS
routes. For example, if a UDP route FRL is 1 and the caller's extension FRL is 0,
the caller is unable to use the route, because the route FRL is higher than the
CAUTION:
Unless networked systems are collocated, each system should have
at least one loop-start line connected to the PSTN. The line is
required to allow connection of a power-failure telephone to the
Power-Failure Transfer (PFT) jack on a module as a power outage
backup and for correct routing of emergency and other N11 calls. To
ensure that the correct services are reached, if the loop-start line is
used for emergency or other N11 calls, it should be assigned to the
main pool. In this case, IXC calls determine the number of loop-starts
required. Refer to Feature Reference guide for details on the PFT
feature.
3
"Remote Access" on page
Issue 1
February 1998
Page 3-3