These frequently asked questions and answers about telephone area codes were originally published on the Federal Communications Commission (FCC) website.
Who is in charge of area codes?
Federal and state regulators share this responsibility. The North American Numbering Plan Administrator is responsible for day to day administration, assignment and management of area codes in the United States.
Congress gave the FCC jurisdiction over telephone number administration in 1996.
The FCC delegated to the states the authority to decide when, and in what form, to introduce new area codes.
Area codes may be added either by a geographic split or by an overlay. (See answer to the following question.)
The FCC receives advice on number administration issues from the North American Numbering Council (NANC), an advisory body made up of industry participants, consumer advocates, and state regulators.
Why do we need new area codes?
The demand for telephone numbers has increased dramatically with the growth of wireless telephone, fax and pager use, and the use of additional lines for Internet access. But this is not the main reason for new area codes.
The 1996 Act marked the beginning of competition for local telephone customers.
Competing local telephone companies, wireless telephone companies, and paging companies all need inventories of numbers before they offer services to customers.
Because of the system set up by the telecommunications industry for and in a monopoly environment, telephone numbers are currently given out in blocks of 10,000.
There are 792 blocks of 10,000 in each area code (792 x 10,000 = 7,920,000 available numbers).
The FCC has concluded that numbers are not currently used in an efficient way. Even if a small percentage of the available telephone numbers in an area code is in use, an area code can run out of numbers if all 792 number blocks are spoken for. The FCC is investigating the most cost-effective way to increase the efficiency and reduce the need for additional area codes.
What will happen if we run out of area codes?
If all of the available area codes are used, our dialing pattern would need to be expanded by one or more digits.
Because changing the dialing pattern in this way would require significant time for transition and would involve substantial expense, the FCC has proposed a number of ways to preserve the life of our current ten-digit dialing pattern for as long as possible.
What is the FCC doing to slow down the pace of adding new area codes?
Area code changes are inconvenient for both residential and business customers, so it is important to make the numbers in each area code last as long as possible.
The FCC is examining several ideas for improving number utilization.
These ideas include improving the information we have about how telephone numbers are being used, and requiring telephone companies to prove that they need new numbers, as well as other, more technical solutions, such as giving telephone numbers to companies in smaller blocks.
For further details, see the Notice of Proposed Rulemaking.
Why do customers in some states have to dial ten digits for every phone call?
Area code overlays can result in two different homes in the same geographic area with the same seven-digit local number, but with two different area codes.
To route calls to the right destinations, customers must dial ten digits.
The FCC has required ten-digit dialing with area code overlays in order to level the playing field, so that new telephone companies can offer their services without suffering a competitive disadvantage.
Without ten-digit dialing, established telephone companies may have an advantage over new telephone companies. Customers could find it less attractive to choose a new telephone company if doing so would mean always dialing ten digits, but choosing an established telephone company would allow them to dial only seven digits.
In addition, ten-digit dialing permits fuller use of all of the numbers within an area code, extending the life of the area code.
If they dial ten digits for every call, how do customers know which calls are toll calls and which are local?
The number of digits in a phone call does not determine whether it is a local or a toll call.
Designation of toll calls varies somewhat among different states.
When in doubt, customers should check the information provided in their telephone directory.
How many numbers are available in each area code?
Each area code has a finite number of seven-digit phone number combinations.
Theoretically, each area code could include 10 million seven-digit phone numbers.
But some numbers are not available — such as seven-digit numbers starting with 0, or 1, or 911.
Therefore, each area code has somewhat fewer than 8 million usable numbers (7,920,000).
How many area codes are available? How many are used?
There are a total of 680 usable area codes available for assignment.
Of that number, 215 are currently in service in the United States (as of June 1, 1999). More than 70 of these may need new area codes within a year or two.
In addition, over 40 area codes are in service in the other countries that participate in the North American Numbering Plan, including Canada and a number of Caribbean nations.
By comparison, there were 119 area codes in service in the United States at the end of 1991.
How are numbers allocated to telephone companies?
AT&T designed the area code system in the 1940s, to make it possible to route long distance calls automatically.
Although the area code system was designed when the telecommunications industry was a monopoly, that system is still in use in today's increasingly competitive telecommunications marketplace.
A telephone number consists of ten digits. The first three digits are the area code, the second three digits are the central office or exchange, and the last four digits are the individual telephone line numbers. There are 10,000 possible combinations of these digits within each exchange.
When a consumer makes a telephone call, the network uses the area code and exchange to determine where to send the call.
The area code tells the network the geographic area in which the called party lives, and the exchange indicates the particular switch, within that area code, to which the call should be routed.
This system for routing calls requires numbers to be given out in blocks of 10,000, because each exchange contains 10,000 telephone numbers.
Can't we use smaller telephone number blocks, like blocks of 1,000?
The network routing system currently relies on allocation of numbers in blocks of 10,000.
In recent months, telephone number portability has been introduced in many cities throughout the country.
Telephone number portability enables consumers to change local telephone companies without having to change their telephone numbers.
It is possible to use the same databases that make number portability possible to apportion telephone numbers to local telephone companies in smaller blocks, such as blocks of 1,000.
This process is known as "number pooling."
What is the difference between the "overlay" and a "geographic split" method of adding a new area code?
Most area codes are added by way of a geographic split. The geographic area covered by an existing area code is split in two (or three). One of the sections retains the existing area code, while others receive new area codes.
The benefit of a geographic split is that an area code remains defined as a geographic area – customers know something about the location of the people they are calling.
The down-side of a geographic split is that many customers must cope with the inconvenience of changing their area code.
An overlay is an alternative way of adding an area. As the name suggests, the new area code "overlays" the pre-existing area code, most often serving the identical geographic area.
The benefit of an overlay is that customers retain their existing area codes. Only new lines get the new area code.
An overlay requires all customers, including those with telephone numbers in the pre-existing area code, to dial area codes for local calls.