Mike's PBX Cookbook

BARS Flowchart

Basic Automatic Route Selection (BARS) / Network Alternate Route Selection (NARS) is used to prevent users from placing unauthorized toll calls, and to route outgoing calls over the least expensive facility available at the time the call is placed.

There are lots of twists and turns on this journey! The following flowchart shows the process...
Use the cursor keys, or click page corner, to turn pages. Source: Nortel Training Material.


Download the full size images: Page 1, Page 2, Page 3, Page 4.

Process:

A user dials the BARS access code, AC1 (9), followed by a number:

  1. BARS tries to match (a portion of) the dialed digits in the tables
  2. If a match is found, a route is determined for the call
  3. FRL (NCOS) is checked (and optionally TGAR)
  4. Digit manipulation is applied (if necessary)
  5. If a trunk is available, the digit string is sent.

If any of the above steps fail, the caller hears re-order (fast-busy).

The overlays:

LD 86 - FEAT: ESN
Define AC1 / AC2 codes
Enable CDP for customer
Second dial-tone (DLTN)
Expensive Route Warning Tone (ERWT)
Check TGAR on BARS calls (default: No)
LD 87 - FEAT: NTCL
Define NCOS to FRL maps (1 to 1)
Define RWTA (expensive tone) for a NCOS
LD 90 - FEAT: NET
Type = NPA (Number plan area code transmission)
Type = NXX (Central Office Code Translation)
Type = SPN (Special Number Translation)
LD 86 - FEAT: RLB
Define Route List (RLI) entries (ENTR = entry #)
LD 86 - FEAT: DGT
Digit Manipulation tables (added to RLI)

Further information: