Prefixes define geographic service boundaries.
The telephony term "prefix" ("central office" or "exchange") defines the geographic area served and the service provider, based on a 10-digit phone number. It is the three numbers after the three-digit area code. The Federal Communications Commission and state government agencies cede telephone numbering authority and management to the North American Numbering Plan Administration (NANPA). You should utilize its database for the most accurate and updated information on local prefixes.
Instructions
1. Click the icon to open an Internet browser, then click the link to open NANPA's "Reports: Central Office Code Reports" webpage (see Resources).
2. Scroll down the webpage and click on "Central Office Code Utilized Report" to advance to the "NANPA Administration System, Utilized Codes Report" webpage.
3. Click the down arrow next to "State," then select the state your are interested in. Pause while the webpage reloads.
4. Click on the down arrow next to "NPA," then select the area code number.
5. Click "Continue" to advance to the results webpage. The local prefixes are under the "NXX" column. The "Rate Center" column provides details on the geographic area associated with that prefix.
