[Asterisk-Users] USA dial plan

[david]

>Yes, in most places in the USA local calls are totally free, no per min
>charge.

This is not true in the US for business lines.  Residential lines have a "free" local calling area.  However, business lines from an incumbent local exchange carrier like SBC nearly always charge rates for 7-digit local calls, usually, but not always based on mileage zones.  Rates vary based on the local carrier, time of day and the distance.  Different rate schemes apply in different parts of the country.  Some use Zone Usage Measured (ZUM) schemes, others use Flat Rate or Measured Rate schemes. There are different rate plans for the same carriers for local toll calls that fall outside the local calling area but are within the same LATA.

Some states do allow 10-digit dialing without a 1+.  Washington DC (202) is an example of this for making local calls to other adjacent area codes.  The entire North America Numbering Plan (NANP) is in a constant state of change as new area codes are added.  There are 4 different dialing plans for each area code that can vary with regard to the number of digits required and whether a 1+ is required:

- Home NPA Local Calls
- Foreign NPA Local Calls
- Home NPA Toll Calls
- Foreign NPA Toll Calls

If you go to www.nanpa.com and click on the "Dialing Plans" option in the left column, you can get the current ("Standard") and evolving ("Permissive") dialing plan for any area code.  For example, 310 is currently setup this way:

Dialing Plan                      Standard                Permissive
- Home NPA Local Calls               7D                      1+10D
- Foreign NPA Local Calls           1+10D                     NA
- Home NPA Toll Calls                7D                       NA
- Foreign NPA Toll Calls            1+10D

This says you currently dial local calls within 310 as 7 digits, but the plan will change to require 1+10 digits which is currently permitted.

Hope this helps 
David Schlossman
david at atcomm.com



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