The Federal Communications Commission (FCC) today released its latest report on telephone number utilization in the United States. Telephone number utilization refers to the percentage of telephone numbers assigned to customers compared to the total of telephone numbers assigned to carriers. The Numbering Resource Utilization Report details how those telephone numbers are being used.
Archive. Archive of released Number Resource Utilization reports .
- Metropolitan Statistical Areas with rate center names. This file lists Metropolitan Statistical Areas (MSAs) and their corresponding rate centers. It uses rate center names as they appear in the January 2001 Local Exchange Routing Guide (LERG). Posted 3/01. MSARateCenterNames.ZIP (139K) 
- Long Distance Carrier Code Assignments. The North American Numbering Plan Administrator (NANPA) provides updated information on Area Codes, ANI II Digits, Carrier Identification Codes, N11 Codes, Vertical Service Codes, Central Office Codes, 456-NXX Codes, 500-NXX Codes, 555-Line Numbers, 800-855 Line Numbers, and 900-NXX Codes. (See http://www.nanpa.com/number_resource_info/index.html ).
- The below reports provide historical information on carrier identification codes (CICs), 500 and 900 service code assignments and the number of toll-free numbers (800 and 888).
- Central Office Code Usage Report. Released 07/93. COCUR93.ZIP (211K) 
- North American Numbering Council 
- Toll-free 800/888/877 Numbers 
- The North American Numbering Plan Administrator  has the most current details on area code changes, carrier identification codes, and other telephone numbering issues.