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Area Code Splits & Overlays

What is an area code split?

The exhausting area code is split into two or three geographic areas, leaving the existing area code to serve on side of the geographic area and assigning one or two new area codes to the other segment(s).

What is an area code overlay?

An area code overlay occurs when more than one area code serves the same geographic area. In an area code overlay, relief is provided by opening up a new area code within the same geographic area as the area code requiring relief. With an overlay, all current customers keep their area code and telephone number. Numbers from this new area code may be assigned to new telephone customers or those adding additional lines. Because two area codes reside in the same geography, all calls must be dialed using the area code + the seven-digit telephone number (10 digits). Some states require 1+10-digit dialing.

What is 10-digit dialing?

10-digit dialing is a term used to refer to the practice of including the area code of a phone number when making local calls. It is the required dialing pattern in locations throughout the country that have undergone an area code Overlay. For example, if area code (123) is overlaid with area code (456), then callers within the area served by 123/456 must dial 10-digits in order to place a local call even if the call is from a (123) number to another (123) number. Pre-subscribed long distance calls still require 1+10-digit dialing. Consumers in areas subject to an Overlay should replace all 7-digit telephone numbers programmed into their wireless phones and other devices with 10-digit telephone numbers.

What is permissive dialing?

The permissive dialing* period begins with the introduction of the new area code and generally lasts approximately six months. It provides a "get acquainted" transition period for the new area code. Permissive dialing allows the old and new area code customers to call between the two area codes using seven-digit dialing. During this period, customers should begin to use the area code + the telephone number, although calls will still complete if only the seven-digit telephone number is dialed. Customers from outside the area can call the new area code by dialing either the old or the new area code + the telephone number; the call will complete during the permissive period. 

*The permissive dialing period varies in length per commission decision.

What is mandatory dialing?

Approximately six months after the introduction of the new area code, an intercept recording* period will begin. At this time, callers must use the appropriate area code plus the telephone number. Calls incorrectly dialed will be referred to a recording throughout the recording period. It will inform the calling party that the new area code must be used to complete the call.

If you have family or friends deployed in the military outside of the United States, make sure they know and use your new area codes.

*The intercept recording period varies in length per commission decision.

How do I know if I'm affected by an area code split or overlay?

Visit the North American Numbering Plan Administrator (NANPA) site to find out more about any area code changes in your region. 

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