Restricting area codes and prefixes

Last Updated : Sep 27, 2016 |

About this task

Certain area code numbers are set aside in the North American Numbering Plan. These numbers are 200, 300, 400, 500, 600, 700, 800, 877, 888, 900. You need to specifically deny calls made to area codes 200 through 900 (except 800 and 888).

You can also deny access to the 976 prefix, which is set aside in each area code for pay-per call services, if you do not want to incur charges. You can block 976 or any other prefix in all NPAs with a single entry in the digit analysis table. See Using wild cards for more information.

Procedure

  1. Set the 200 area code apart from other area codes 201 through 209.

    We use the digit analysis table 120 because it defines long distance calls that begin with 1 and all area codes from 200 through 209.

  2. To deny long distance calls to the 200 area code, type change ars analysis 120.
  3. Press Enter to view the ARS Digit Analysis Table screen beginning with 120.

    The table (on the screen) in this example shows two translations for calls that begin with 120.

    First, follow the routing for a long-distance call that begins with 120 and is allowed. The 120 translation handles all dial strings 1-201 through 1-209, and there are many matches.

    • A user dials 9 120 plus 8 digits (the first of the 8 digits is not 0).

    • Communication Manager drops the ARS FAC (9 in our example), looks at the ARS Digit Analysis Table for 120, and analyzes the number. It determines the call is long-distance and sends the call over route pattern 4

    Now we will follow a call that begins with the restricted area code 200. Only one string matches this translation.

    • A user dials 9 1200 plus 7 digits.

    • Communication Manager drops the ARS FAC (9), and looks at the ARS Digit Analysis Table for 1200. It determines that the call type is deny, and the call does not go through.