# Set RCOS System-Wide Parameters

To enter the starting and ending NPA (area code) and NXX (three-digit prefix) digit positions:

1. Complete an RCOS worksheet.

2. From the Main Menu, select (S) System Maintenance, (R) Reconfiguration, (M) Restriction COS, and then (D) Define System Wide Parameters.

3. Count an example dial string your server can use to locate the starting and ending digit positions for the NPA (area code) and the NXX (three-digit prefix). For example, the settings for a North American ten-digit phone number are:

   - The starting NPA digit position is 10

   - The ending NPA digit position is 8

   - The starting NXX digit position is 7

   - The ending NXX digit position is 5

4. Select (A) Starting Digit Position of NPA and enter the n umber of the digit position at the start of the NPA.

5. Select (B) Ending Digit Position of NPA and enter the n umber of the digit position at the end of the NPA.

6. Select (C) Starting Digit Position of NXX and enter the n umber of the digit position at the start of the NXX.

7. Select (D) Ending Digit Position of NXX and enter the n umber of the digit position at the end of the NXX.

8. Exit the RCOS menu to save your settings.

- Configure an RCOS