The FCC recently asked for comments on a petition by Country Code 1 ENUM LLC to obtain North American Numbering Plan numbering resources, i.e. PSTN phone numbers, for testing of an ENUM system. (Depending on your view, ENUM is short for either E164 Number Mapping or tElephone Number Mapping.) Country Code 1 is a consortium organized "to build the public infrastructure that will promote the development of ENUM technology in a single, carrier-class manner within the [NANP] countries" (which include the United States, Canada and the Caribbean nations).
PSTN phone numbers arenormally only given to telecom carriers, which Country Code 1 is not. This petition may be the camel's nose under the PSTN tent. It directly implicates the issue of control of the database or databases that facilitate contact among the members of a network or group of networks. Customers may contact people or businesses in a variety of ways: by dialing their PSTN phone number, by typing their e-mail address in an e-mail program, or by clicking on their instant messaging name. Each of these identifiers is connected through a database—the PSTN numbering system, the domain name registry, and the IM presence database. Today, these databases are controlled by different entities, and control of the database is a an important competitive factor.
In the future, all of these may be unified through ENUM. ENUM employs a system for routing that is similar to the domain name system used for Web addresses. It allocates a single identifier, consisting of both letters and numbers, that can then be used for multiple IP services, such as VoIP, e-mail, and instant messaging. In an ENUM environment, if you enter a PSTN phone number into your cellphone or an e-mail address into your computer, the ENUM software can map that number or e-mail address to the ENUM identifier and deliver information about all the possible ways to contact the owner of that number or e-mail address. The caller can then choose one of those connections and be charged appropriately.
The beauty, and the threat, of ENUM is that it minimizes the importance of a PSTN phone number by making it simply one option to be used in contacting a party. It allows that phone number or an IM screen name or an email address to be used to route a call, e-mail, or instant message on a network other than the PSTN. When combined with relatively simple least cost routing software, ENUM implementation that is not controlled by incumbents will inevitably hasten the ongoing decline of PSTN revenues, particularly the incumbents’ above cost charges for termination of voice calls.