Area Code Relief

The rapid growth in demand for telephone numbers has resulted, in many places, in a condition known as area code “exhaust.”  An area code reaches exhaust when all of the available central office codes within that area code have been assigned.  Area code relief, by means of an overlay or geographic split, must then be implemented to ensure that an adequate supply of telephone numbers remains available for assignment.

Telephone Number Basics

Our telephone numbering system operates under the North American Numbering Plan.  That plan, developed in 1947 by AT&T, and subsequently adopted by the Federal Communication Commission (FCC), established the 10-digit scheme we use today:

(e.g., the PSC’s number is 608-266-5481)
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Area CodeCO CodeLine Number 
  • The “NPA” (Numbering Plan Area) is the area code.  Wisconsin currently has 6 area codes: 715, 534, 414, 608, 920, and 262.  An area code cannot begin with a 0 or a 1.
  • The “NXX” is the central office (CO) code, also referred to as the “prefix.”  An NXX serves a specific exchange or rate center.  For a CO code, N = 2-9 and X = 0-9.
  • The XXXX is the line number for a customer.  For these numbers, X = 0-9, thus, in any NXX code, there are potentially 10,000 line numbers available for assignment: 0000-9999.

What is an Area Code?

An area code is the first 3 digits of a standard 10-digit telephone number. Area codes are also known as Number Plan Areas (NPAs). In Wisconsin, there are 6 area codes in service; 262, 414, 608, 715, 534 and 920. A new area code (274) that will eventually serve the same geographic area as 920 has been approved; however, a firm implementation schedule for its introduction has not yet been set.

Why are we running out of numbers?

In recent years, the prevalence of technology in everyday life has increased tremendously.   Many households no longer have a single phone number for the entire family.  Instead, customers often have multiple telephone lines, multiple cell phones and Internet access.  The combination of new technologies (i.e. OnStar, Voice over Internet Protocol), new telecommunications providers requiring their own telephone numbering inventories and the increased demand for telecommunications services in general (such as cellular phones, pagers, fax machines, modems, alarms and internet access) have strained our existing telephone number resources, both in Wisconsin and across the country.

Specific questions pertaining to your telephone service should be directed to your local service provider at the number printed on your billing statement.  General questions and comments regarding area codes can also be referred to the PSC.


  • Documents associated with either the 715 area code relief plan (Docket 5-TN-100) or the 920 area code relief plan (Docket 5-TN-106) may be viewed on the PSC website.
  • General questions may be directed to the docket coordinator: Peter Jahn, at Peter Jahn, or (608)267-2338.