1200 W. Washington Street

Phoenix, AZ 85007-2927


Phoenix Office: (602) 542-4251


Tucson Office: (520) 628-6550


Toll Free In-State Only:

1-(800) 222-7000


Email: UtilitiesDiv@azcc.gov

The use of inappropriate or threatening language when submitting a complaint to the above email may result in your comments not being docketed and no action taken regarding your comments


All About Area Codes Answers to Common Questions


An area code is the first three digits of your telephone number. For example, in Arizona, 480 is an area code. Area codes were first developed in the late 1940s in order to meet the post-World War II surge in demand for telephone service. There are 792 area codes. A prefix is the three digits of your telephone number that follow the area code. A prefix can begin with any number other than 0 or 1 and cannot end with 11 (as in 911 or 411 – as these are reserved for special uses). There are 10,000 possible combinations for the final four numbers (all the possible combinations from 0000 to 9999). A nationwide map of area codes is located at the following web address: https://nationalnanpa.com/area_code_maps/ac_map_static.html.

Who oversees the assignment of area codes?

The North American Numbering Plan Administrator (NANPA) tracks the consumption of telephone numbers and assigns new area codes as necessary.


Due to numbering resource demands, the 480 Numbering Plan Area (NPA), or Area Code, is projected to exhaust its supply of Central Office Codes by the first quarter of 2024. Because the 480 NPA is within 36 months of this projected exhaust, according to NPA Code Relief Planning and Notification Guidelines, NANPA convened an Arizona telecommunications Industry (Industry) relief meeting on April 28, 2021. The meeting attendees discussed the relief alternatives and reached a consensus to recommend to the Arizona Corporation Commission (Commission) a Boundary Elimination Overlay as the proposed form of relief.

On June 8, 2021, NANPA filed an application with the Commission on behalf of the Industry requesting the Commission approve the Industry consensus of a NPA Boundary Elimination Overlay as the plan for relief for the pending exhaust of numbering resources for the 480 NPA or Area Code.

In 1999, the Phoenix rate center1 was split from the 602 NPA into three NPAs, creating the 480 and 623 NPAs. The 480 NPA serves the southcentral area of Arizona including, but not limited to, a portion of the City of Phoenix, Chandler, Gilbert, Mesa, Tempe, Scottsdale, and Sun Lakes in the counties of Maricopa and Pinal. The 602 NPA borders the west side of the 480 NPA, serves the majority of the City of Phoenix as well as, but not limited to, a portion of the City of Glendale, and the communities of Cave Creek and Ahwatukee. The 623 NPA borders the west and north sides of the 602 NPA, the west side of the 480 NPA and serves the areas of, but not limited to, the City of Glendale and the communities of Avondale, Tolleson, Buckeye, Sun City and New River.

1 A rate center is a geographical area used to determine the boundaries for local calling, billing, and assigning specific phone numbers, which can encompass multiple area codes.

A Boundary Elimination Overlay is a form of NPA relief in which the boundary between existing non-exhausting NPAs and the exhausting NPA is eliminated such that all the area codes serve the same geographic area, forming an overlay over each other. The boundary elimination in this case would result in the boundaries between the 480, 602 and 623 NPAs being removed, and would require 10-digit dialing within and between the affected area codes.

Advantages for the Boundary Elimination Overlay include:

  • It eliminates the need to open a new NPA for the 480 NPA area.
  • As the 602 NPA is projected to exhaust in the second quarter of 2026, thus kicking off another round of relief planning in the second quarter of 2023, this option would eliminate that need along with the need to open an additional NPA for the 602 NPA area.
  • It does not require existing customers to change their area code/phone number.
  • It removes the 3-way split of the Phoenix rate center, making it one rate center again.
  • As the boundary elimination will require 10-digit dialing for 602 and 623 NPAs, and the Federal Communications Commission’s (FCC) requirement for 10-digit dialing for the National Suicide Hotline implementation of the 988 3-digit code requires the 480, 520 and 928 NPAs to transition to 10-digit dialing, it creates a consistent 10-digit dialing plan across the entire State of Arizona. 2
  • It is a more efficient use of resources.
2 See In the Matter of Implementation of the National Suicide Hotline Improvement Act of 2018, WC Docket No. 18-336, released July 17, 2020.

Challenges for the Boundary Elimination Overlay include:

  • It requires customers in the 602 and 623 NPAs to dial 10-digits where otherwise, based on current exhaust projections, customers wouldn't be subjected to NPA Relief and 10-digit dialing for another five years for the 602 NPA and 48 years for the 623 NPA.
  • The loss of the ability to associate an area code with a unique geographic area.

On November 2, 2021, the Commission issued Decision No. 78311 ordering the Boundary Elimination Overlay Relief Plan involving the 480, 602 and 623 area codes be adopted and implemented.

What is 10-digit dialing?

Ten-digit dialing simply means that instead of dialing 7-digits of a telephone number, you will need to dial all 10-digits of the number in order to complete a local call. In other words, you will need to start including the area code when you dial a local call.

Who will this affect?

As customers in the 480 Area Code are already completing calls via 10-digit dialing, this will only affect customers in the 602 and 623 area codes. This will not affect any other customers in any other of the Arizona area codes.

I’m a customer in either the 602 or 623 area codes. When do I have to start dialing all 10 digits?

Beginning February 11, 2023, you should start dialing 10-digits (area code + telephone number) for all local calls. If you forget and dial just 7-digits, your call will still be completed.

Beginning August 12, 2023, you must dial 10-digits (area code + telephone number) for all local calls. On and after this date, local calls dialed with only 7-digits may not be completed, and a recording will inform you that your call cannot be completed as dialed. If you get this recording, you must hang up and dial again using the area code with the 7-digit telephone number.

What will *not* change?

• Your telephone number, including current area code, will not change.
• The price of a call, coverage area, or other rates and services will not change.
• What is a local call now will remain a local call regardless of the number of digits dialed.
• You will continue to dial 1+ the area code + telephone number for all long-distance calls.
• Callers will still be expected to dial a prefix (such as “9”) when dialing from a multi-line telephone system (i.e., in a hotel, office building, etc.) as required.
• You can still dial just three digits to reach 711 (relay services), 911 (emergency services) and 988 for the National Suicide Prevention Lifeline.
• Any 211, 311, 411, 511, 611, or 811 services available in your community can still be reached by dialing the 3-digit code.

I still have questions. Who can I contact?

If you have any questions regarding this information, please call your local telephone service provider for more information. They are responsible for ensuring this dialing change goes into place. You can also contact the Commission’s Phoenix office at 602-542-4251, toll free at 1-800-222-7000 or via email at UtilitiesDiv@azcc.gov.


Will Arizona ever need new area codes?

Occasionally an area code runs out of available telephone number prefixes. Competition and new telecommunications service providers entering the market increase the demand for available numbers. In addition, the rapid proliferation of cellular phones and Internet-based telecommunications services is accelerating the use or consumption of these numbers.  All of these factors can mean that there will be fewer and fewer numbers available.

Why can't you assign the new area codes to pagers, faxes and cell phones?

The FCC will not allow a specific area code to be assigned to pagers, cellular telephones and faxes. FCC rules prohibit the assignment of telephone numbers based solely on a group's specific type of telecommunications service or the use of a particular technology.

Who decides which areas receive the new area code?

The Commission  makes the final decision. NANPA notifies the telecommunications industry when a particular area code is projected to run out of prefixes. Telecommunications service providers begin meeting to identify possible solutions to the problem. The industry then brings their recommendations to the Commission.

So, what are the options?

There are two options for implementing a new area code: a geographic split or an overlay.

What is a geographic split?

A geographic split essentially draws a line through an existing area code and assigns a new area code to customers on one side of the line. The other side of the line would retain their existing area code. This requires many customers to change their telephone numbers and distribute the new telephone number to all their contacts.

Businesses will have to reprint stationery, business cards, brochures, checks and other printed materials. Residential consumers will need to alert their friends, family, and businesses they use to let them know the new area code.

What is an overlay?

An overlay adds a new area code to an existing geographic region. This means that two area codes will work in the same general area. New customers would be assigned the new area code. In some circumstances, customers may be able to choose between the old area code and the new one.

How are customers affected by an overlay?

All existing telephone numbers will remain the same. Businesses don't have to reprint their stationery, business cards, and brochures unless they are adding a new public telephone number. Adding an overlay code means that you will need to dial all ten digits of the telephone number to complete a local call. The ten digits include the area code plus the 7-digit number.

Will I be charged toll rates for calls to the new area code?

 No, not if the call was a local call before the new area code was introduced. Calls that are toll calls now would remain toll calls. For example, calls from Tucson to Phoenix would still be toll calls.  By law, call rates cannot be increased solely as a result of an area code split.

Will I have to change the way I dial emergency, directory assistance or long-distance numbers?

Emergency dialing and directory assistance would not be affected. You would simply dial 911 or 411 as usual. You would still dial 1 + area code + seven-digit number to complete a long-distance call. Cell phones require ten digit dialing.

How is a new area code implemented?

Implementing a new area code involves two steps designed to familiarize telephone users with the change. The introductory period is called "Permissive Dialing" which begins with the introduction of the new code and lasts several months.

  • With a geographic split:
    * Permissive Dialing allows the old and new area code to be used interchangeably.
    * The second phase is called "Mandatory Dialing" at which time callers must use the correct new 10-digit telephone number to call telephone numbers outside their area code. Local calls within the same area code can be completed by dialing only the 7-digit number. Callers who do not dial the proper telephone number will hear a recording announcing the change.
  • With an overlay:
    * A Permissive Dialing period is also used with an overlay and allows the customers to being using 10-digits even though the calls will go through if only the 7-digit number is dialed.
    * Once Mandatory Dialing starts, callers are required to dial the 10-digit number on all calls. Callers who do not dial the proper number will hear a recording announcing the change.

What are some of the pros and cons of a geographic split?

Pro: Ten-digit dialing is necessary when calling another area code or when making a toll call.

Pro: Area codes have a geographic identity. People can get an idea of where a business or individual is located by looking at their area code.

Con: Existing telephone numbers change -- approximately half of the people have to change their telephone numbers. Each time there is a geographic split, businesses have to pay to reprint all of their literature, promotional items, stationery and business cards to include the new number.

Con: As more and more numbers are used up and as the state continues to grow, the "slicing and dicing" of a specific area will continue. Geographic splits are not long-term solutions and future area code relief must be undertaken. For example, the Chicago metro area used to be served by just the 312 area code. Now they have this arrangement:

  • 312 = Downtown Central Chicago
    773 = Remainder of Chicago
    847 & 224 = Northern Chicago suburbs
    708 = Southern Chicago suburbs
    630 = Central Chicago suburbs

What are the pros and cons of an overlay plan?

Pro: Only new customers or businesses or individuals requesting new lines get the new area code. All existing telephone numbers remain the same. No one has to incur the costs of changing their printed material.

Pro: An overlay may be a long-term solution since an overlay would be used in future numbering exhausts. New area codes are simply placed over the affected area with each impending exhaust.

Con: People have to get used to dialing all 10 digits all of the time. The exception is when you dial special use numbers like 911 for emergencies or 411 for directory assistance -- these do not require an area code.

Con: Businesses and individuals will need to reprogram certain phone systems, burglar alarm systems and other equipment to accommodate 10-digit dialing. Businesses and individuals may have more than one area code for their lines.

Stay Connected

Check here to sign up for Consumer Alerts from the Corporation Division. To receive alerts for your business register at eCorp.azcc.gov.Please call 602-542-3026 with questions for the Corporations Division.

Check here to sign up for Notices and Agendas for Commission Meetings, Hearings and Appearances.Please call 602-542-3931 with any questions.

Check here to receive the latest Commission News Releases and information. Please call 602-542-0728 with any questions.

Arizona Corporation Commission

1200 W. Washington Street

Phoenix, AZ 85007


Corporations Division

1300 W. Washington Street

Phoenix, AZ 85007


Tucson Office (Walk-ins only)

400 W. Congress Street

Tucson, AZ 85701