Information Resources and Technology Management


You are invited to read the definitions of terms used in this data standard.

Telephone Number
A ten-digit number assigned to a person or place for the purpose of communicating by telephone in a geographic area that is part of the North American Numbering Plan (NANP). The number is comprised of a three-digit area code, a three-digit prefix that represents a local exchange, and a unique four-digit number that is often referred to as the extension.  
Type Area Code:  Integer

Telephone:  Character Field

Syntax Area Code:  NXX, where N represents any digit from 2 through 9, and X is any digit from 0 through 9. The first digit of the area code is always a number from 2 through 9; a leading "0" or "1" is not permitted.

Telephone:  NNN-NNNN, where each N represents a number from 0 through 9.  A hyphen shall be used to separate the three-digit telephone prefix from the unique four-digit number.

Recommended Field Name Area Code:  AREACODE

Telephone:   TELEPHONE

Historical Data For information on past versions of this standard, contact the Chief Data Officer

Part 270, FW 6, Data Management and Standards, has been superceded by Part 274, FW 2, Establishing Service Data Standards.

NANPA Web site - provides information about the NANP and its administration. The NANP is the numbering plan for the Public Switched Telephone Network of the United States and its territories, Canada, Bermuda, and many Carribean nations. Numbering plan area (NPA) codes (i.e., area codes) in service are listed by number and location, and area code maps are available for downloading.

Use Instructions
As of the approval date, this data element will be used in any new automated system, data set, database, or information application, including new Geographic Information System (GIS) data and applications. This data element will also be used in any major modifications to existing systems or versions of these data-related items that include area codes and telephone numbers for geographic areas in the NANP. This includes Canada, the United States, the District of Columbia, and the following United States territories and associated areas: Guam, Northern Mariana Islands, Puerto Rico, and the Virgin Islands of the United States.

This data element standard also applies to ten-digit cellular (CELL), facsimile (FAX), and TTY (Teletypewriter) or TDD (Telecommunications Device for the Deaf and Hearing Impaired) numbers.

Service staff are strongly encouraged to utilize this data element in existing systems, data sets, databases, and information applications. Where existing systems and data-related items are not in compliance, they should be modified to achieve compatibility and implement this data standard.

The three-digit area code and seven-digit telephone number will be handled as separate data fields, and will not be combined in a single data field. 

The United States territory of American Samoa, the freely associated states of Federated States of Micronesia and Marshall Islands, and the trust territory of Palau are not part of the NANP and, therefore, require all (or a subset of) the following: International Access Code, Country Code, City (routing) Code (when applicable), and the local telephone number. Refer to the proposed data standard, International Telephone Number, for syntax and specific use instructions on telephone numbers for these and other geographic areas outside the NANP. 

Approval Date
November 13, 2000
Validation Date
November 29, 2013
Data Steward
Chief Data Officer


Last updated: May 9, 2019