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

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

Number Portability Collates information on the regional initiatives in place to develop number portability and number pooling in the US. http://www.ported.com/

World Telephone Numbering Guide Detailed information and news on public numbering plans from around the world. http://phonebooth.interocitor.net/wtng/

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

Active Numbers Online OFTEL UK numbering allocations, North American area codes and country codes, with associated tariff information. http://www.active-numbers.com/

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

NumberPooling.org Number pooling resource center that aggregates number pooling information from a variety of sources, including an events calendar, roles of various groups, related FCC rulings, acronyms, a glossary, information by state, region or nation. http://www.numberpooling.org/

Alpha Net Provides comparison of Israel's international phone company rates in both online and downloadable form. http://www.alphanet.co.il/public