There are a limited number of combinations of prefixes that are available to be used with an area code.  Some prefixes are unavailable due to being used for public access information such as 911 or 411.  Prefixes, also called codes, are assigned and are specific to, geographic locations which are called rate centers.  That means that a prefix that has been assigned to one geographic location or rate center is not available in another rate center.  Some rate centers run low on prefixes and require more prefixes. At some point there are no additional prefixes that are available for assignment.  When there are no more prefixes available for assignment, more numbers must be made available and this means the addition of another area code.

There is a lengthy planning process that the industry, the FCC through its’ numbering contractor, the North American Numbering Plan Administration (NANPA) and the CPUC undergo to determine the most appropriate way of introducing a new area code.  Public input is sought both through meetings held in the locality affected and through the CPUC’s website.  When the information about the best option for introducing a new area code is fully developed, NANPA applies to the CPUC for a new area code.  The CPUC takes that information and information that has been developed from the public and approves an area code addition and method.  At this time, area codes are added either by a geographic split, which has been the historical practice, or through an area code overlay.

Traditionally, the geographic area that an area codes is assigned to have been split to provide more prefixes for the telecommunications industry and its customers, thus creating smaller geographic areas. Area code splits create new area codes by splitting a geographical region into new, smaller regions. Usually the splits are in two ways with one region keeping the same area code and the other region changing to a new area code.

With the split method of introducing a new area code, a given location will only have one area code.

An area code overlay is a form of area code change that typically adds a second area code to the same geographic region. Therefore, multiple area codes can co-exist within the same geographic region. People with telephone numbers within the exhausting area code will retain their current telephone number(s) and area code. Individuals that would like to have new or additional telephone numbers or telecommunications services may be given telephone numbers with the new overlaid area code.

If you have a telephone number within an area code that is running out of prefixes, you will be affected by an area code change regardless of the area code change option implemented.

If an area code split is implemented then some individuals will have to change their area code to the new code. This depends on whether the individual telephone is located in the area designated for the new area code.

If an area code overlay is implemented then individuals will be able to retain their current telephone number and area code, but will need to dial 1+ the area code and the telephone number for all calls. This ten +1 digit dialing protocol is a change from the current seven digit dialing that customers use to make local calls.

This form of area code assignment is referred to as a technology-specific overlay.

Currently customers changing their service from a landline phone to a cellular service may move their telephone number from the landline phone to the cell phone as long as both services are in the same geographic area.  Customers may also change their cell phone number to a landline within the same geographic area.  This is called local number portability.  Local number portability between landline and wireless services would not be available if technology-specific overlays were implemented.

In September 2005, in response to the CPUC’s third request for authority to implement a technology-specific overlay, the FCC partially granted the CPUC’s request. However, the FCC did not grant the CPUC authority to permanently maintain seven-digit dialing in the geographic region(s) where the technology-specific overlay would be implemented. Moreover, the phone numbers associated with wireless services were excluded from the list of those phone numbers that would get a separate area code. The FCC's partial granting of the CPUC's request did not include other important elements of the CPUC's proposal. As a result, the benefits of implementing the technology-specific overlay the FCC authorized, did not outweigh the customer costs of implementing the FCC-imposed requirements.

The new area code is selected by the North American Numbering Plan Administrator.

The telecommunications industry, will be updating the directory listings in the white pages for all affected communities to identify the associated area code of a telephone number. Individual customers are responsible for any changes to listings appearing in other directories. Each customer is responsible for telephone numbers appearing in any display advertising.

The CPUC does not decide in advance which region will receive the new area code if an area code split is implemented, and it weighs various factors in making that decision.

If an area code overlay is ordered, those consumers who order new telephone numbers or services will most likely receive the new area code if the CPUC implements an area code overlay.

Telephone numbers with the new area code are available after the implementation of the area code change is completed.

No. Typically the area code relief process takes at least one year before the new area code is ready for implementation.

No, if an area code split is implemented.

Yes, if an area code overlay is implemented. Individuals must dial 1 + the area code and the telephone number for all calls. All local calls, whether made to a telephone on the same block, next door or within the same house, must dial 1 + the area code and the telephone number.

The Federal Communications Commission (FCC) requires dialing the area code + telephone number for all calls where an area code overlay exists. The FCC believes that this would maximize numbering resource optimization, minimize anti-competitive effects due to dialing disparities, and avoid customer confusion.

Dialing the “1” before the telephone number signals to the telephone company routing system that your call will be going outside the area code rather than to a prefix within your area code.   Use of the additional “1” allows your call to be transmitted in the most expeditious way possible.

No. individuals can still just dial only three digits to reach 9-1-1. No additional digits will be required to make emergency calls.

No. Individuals can still just dial only three digits to call N-1-1 phone numbers such as 211, 311, 411, 511, 611, and 711.

If you will receive a new area code,

  • Reprogram any equipment or features i.e., automatic dial, speed-dial, call forwarding, modems for computer or internet dial-up access, etc., that use a telephone dialer.
  • Update items like stationery, checks, etc. to include the new area code
  • Advise families, friends, etc. to dial the new area code.
  • When asking for someone else’s number, remember to ask for the area code too.
  • Check with your service provider if manual or over-the-air reprogramming of your cell phone is needed to account for the new area code.

  • Contact security or alarm vendors, to update dial-up numbers to avoid a break in security routines and contacts.
  • Reprogram equipment or features i.e., automatic dial, speed-dial, call forwarding, modems for computer or internet dial-up access etc., programmed to dial seven digits to dial "1" + area code + telephone number.
  • Update items like stationery, checks, etc., to include your area code + telephone number.
  • Start thinking of dialing 1 + the area code + telephone number for all calls.
  • Advise families, friends etc., to dial 1 + the area code + telephone number for all calls.
  • Provide your area code + telephone number, not just the telephone number, as needed.
  • When asking for someone else’s number, remember to ask for the area code too.
  • Remember that the previous area code and the new area code will co-exist within the same geographic region.

  • Notify alarm service providers of the appropriate area code + telephone number(s) so alarm service records and equipment can be updated as needed.
  • Ensure security door and gate systems are reprogrammed to dial "1" + area code + telephone number.
  • Reprogram any call-forwarding, automatic-dial or speed-dial features to dial "1" + area code + telephone number.
  • Test telephone equipment to determine if it can dial and receive "1" + area code + telephone number. Questions regarding changes in telephone equipment should be directed to telephone equipment vendors.
  • Update items like stationery, checks, business cards, advertisements, promotional items, brochures, internet web pages, catalogs etc., to include your area code + telephone number.
  • Teach employees, coworkers, customers etc., to dial the area code + telephone number for all calls.
  • Provide your area code + telephone number to your business contacts, not just the telephone number.

Individual consumers are responsible for these costs.

No.

Calls that were local before the area code change will remain local calls. The distance, time of day, and length of a call determine the price of a call.

It is possible for there to be special charges if an individual dials a "0" before the area code + telephone number. There may be special operator-assisted rates or credit card rates for this type of a call. It depends on your telecommunications service provider. Check with your service provider for additional information.

The links on the previous page indicate which area codes are scheduled for or recently had an area code change.  Area where additional codes might be added in the coming years are listed in the Area Code Exhaust Forecast.

View this information in a pdf

Modified 3-10-2008