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How ARS Works
You hear an inside dial tone on an SA button and you dial the ARS access code (usually a 9) to connect to ARS, then you dial a call. If the extension is restricted or toll-restricted and the number dialed is not on the Allowed List, or if the number dialed is on the Disallowed List, you receive a system error tone. Otherwise, ARS compares the number dialed with information in the tables. All tables are available for use at first. Tables are then eliminated from possible use on the call, one by one, until the best table is selected.
Once the table is selected, ARS chooses the appropriate subpattern and checks restrictions, eliminating from consideration any routes with restriction levels higher than the extension�s. Any remaining eligible routes are scanned from the beginning of the list. The first eligible route that is not busy is selected.
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Equal access calls (Interexchange or IXC calls), Dial 0 calls, and N11 calls from systems that are not connected to the public switched telephone network require special planning. See Tandem Switching for details. |
