Instruction manual

Automatic Route Selection (ARS)
Calls are checked to determine if they are international calls or operator calls. Dialed numbers “01”
or 011 signify international calls, “0” plus a number other than “1” signify operator calls (00 calls
signify Intra-Lata operator calls). If the call is an international call and the terminal is not restricted,
the international routing pattern is selected and the call routed accordingly. Operator calls are
routed via the local CO facility.
Calls within the Home Area Code are checked to determine if a special W11 service code (N = 0-8)
has been dialed. Dialed W11 codes assigned a routing pattern are routed via the routing pattern. All
other call types are checked against the Home Area Code Exception Lists. There may be up to four
of these lists, each with an associated ARS Routing Pattern. Up to 800 3-digit office codes may be
divided among the four lists (eight entries may be 7-digit numbers). If a match is found, the call is
routed via the associated ARS Routing Pattern. If no match is found, the dialed number is routed
via the Home Area Code pattern (specified in the Area Code Routing Table), or if none is specified,
via the local CO facility.
If a number is entered more than once in the exception list, the pattern used will be the pattern
associated with the more specific number.
The Area Code Routing Table is simply a listing of North American Plan Area Codes and Special
Number Area Codes, each having an associated ARS Routing Pattern (all pre-1995 North
American Area Codes are assigned routing pattern 1 by default). A dialed Area Code that is listed in
the table is routed using the associated pattern. Calls to Area Codes not listed are routed via the
local CO facility.
The dialed non-local numbers without a route assigned are checked against the Other Area Code
Exception List. Up to 512 entries maybe assigned to the list. Each entry must consist of a 3-digit
NPA code, 3-digit CO code, and two additional digits (for a total of 8 digits). The last four digits may
be “.”, which matches any digit. Each entry has an associated ARS Routing Pattern. If a match is
found, the call is routed using this pattern. If no match is found, the call is checked against the NPA
Routing Table. A dialed NPA that is listed in the table is routed by using the associated pattern.
Numbers that don't match are routed via the local CO facility.
ARS Routing Pattern Table
Figure 2-9 provides a block diagram of an ARS Routing Pattern. Up to eight of these patterns may
be administered in the system. Each pattern consists of two subpatterns that maybe chosen based
on the time of day. Each subpattern (A and B) can contain up to three allowed routes. If all routes in
a subpattern are busy, a CO overflow flag (when set) allows the call to be routed via the local CO
facility; otherwise, the call will queue on the first route in the subpattern.
Administrable Start and Stop times (Hour and Minute) for Routing Subpattern A specify when
Subpattern A should be used to route calls. Subpattern B is used to route calls at all other times.
Each route is specified by its trunk group facility access code or Virtual Facility code and an
associated FRL.
November 1995
2-59