How do calls access the Auto Route Selection (ARS) routing tables?

Question

Options

• ABy using Dial Plan Parameters
• BBy using the Public Unknown Numbering table
• CBy using a Feature Access Code
• DBy using the Toll Analysis table

• A
  4% (1)
• B
  4% (1)
• C
  92% (22)

Explanation

Calls access ARS routing tables by dialing a Feature Access Code (FAC) - typically a single digit like "9" for an outside line - which acts as the trigger that hands the call off to the ARS system for analysis and route selection. Without dialing this FAC, the PBX has no signal to engage the ARS process.

Why the distractors are wrong:

• A (Dial Plan Parameters): These define the structure and length of dialed strings but don't initiate access to ARS routing tables themselves.
• B (Public Unknown Numbering table): This table handles calls where the calling party number format is unrecognized; it's a lookup table, not an access mechanism for ARS.
• D (Toll Analysis table): This table operates within the ARS process to classify calls as local or toll - it's consulted after ARS is already engaged, not how ARS is initially accessed.

Memory tip: Think of the FAC as the front door to ARS - you have to knock (dial the code) before the routing logic inside can do its work. "FAC = First Access to Call routing."

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