Area Code and Numbering

The North American Numbering Plan (NANP) is the telephone numbering system for the Public Switched Telephone Network in the United States, Canada, and some Caribbean countries. NANPA numbering resources are administered by the North American Numbering Plan Administrator (NANPA). The NANP is divided into smaller Numbering Plan Areas that are each identified by a three-digit code, commonly known as an area code. Telephone numbers in the NANP are structured in the format NPA-NXX-XXXX, in which

  • NPA (Number Planning Area) is the 3-digit area code that identifies a specific geographic area;
  • NXX is the term used typically to represent the 4th-6th digits of a ten-digit telephone number (N = any digit 2-9, X = any digit 0-9); for example the NXX Code in 207-287-3831 is 287.  An NXX Code consists of 10,000 numbers or 10 blocks.
  • XXXX is the 4-digit line number that identifies a specific line within a central office.

The Federal Communications Commission (FCC) has exclusive jurisdiction over telephone numbering in the United States but has delegated specific authority to state regulatory agencies. MPUC Staff track daily activity reports from NANPA to assess block or NXX Code requests from providers.   When possible, the Commission works with the provider seeking numbering resources and a provider in the rate center that may have additional capacity to share and donate back to the numbering pool to help extend the life of the 207-Area Code.

Relevant Cases or Dockets

Docket Case Title

MPUC Docket 2020-00192

Commission Initiated Investigation into Current Carrier Numbering Inventory and Compliance with 47 C.F.R. Section 52.50

MPUC Docket 2020-00026

Commission Initiated Inquiry into Preservation of the 207 Area Code

FCC Docket 99-200

Petition by the Maine Public Utilities Commission for Additional Delegated Authority to Implement Number Optimization Measures in the 207 Area Code and Comments in Support of the Petition by the New Hampshire Public Utilities Commission for Additional Delegated Authority to Implement Number Optimization Measures in the 603 Area Code

FCC Number Resource Optimization Orders

(Source NANPA)

Listed below are Federal Communications Commission (FCC) orders that impact the assignment and administration of NANP resources.