Web Directory

» 800 Service Management System
   Information about the central database for US toll free number management.
   http://www.sms800.com/

» Area Code Information
   Detailed information on the history and current developments in North American NPA allocations.
   http://www.areacode-info.com/

» International Numbering Plans
   A collection of all international numbering plans in the world. Some features require a paid subscription.
   http://www.numberingplans.com/

» The Telephone Exchange Name Project
   The historical relationship between North American telephone exchange names and numbers.
   http://ourwebhome.com/TENP/TENproject.html