IETF spec could propel Internet telephony

Think of it as directory assistance for the Net.

The Internet engineering community has developed a technology that lets you type a telephone number into your Web browser and find a corresponding URL, e-mail address or IP address. Called Enum, the new technology integrates the world's telephone numbering plan with the Internet's Domain Name System (DNS) to power a new class of online telephony services.

The Internet Engineering Task Force (IETF) published its Enum specification as a proposed standard in September. Last week, Telcordia Technologies and VeriSign announced the first large-scale test of Enum services. And network vendors such as Cisco, Lucent and Nortel Networks are expected to ship Enum-compliant products next year.

Why all the buzz about Enum? Because it's considered a key enabling technology for the anticipated convergence of the public switched telephone network and the Internet.

For corporate network managers, Enum offers the potential for each employee to have a single contact for communications devices, including PCs, fax machines, handheld computers, cell phones and pagers.

"Enum may enable the corporate phone group to manage the mapping between phone numbers and per-user lists of URLs, where the URLs tell the caller how to contact the callee via phone, e-mail, fax, etc.," says Scott Bradner, director of the IETF's transport area. "Enum puts this under the control of the corporate phone person, not the phone company."

Enum is a simple service that functions like a large database. When an end user types a telephone number into an Enum-enabled application, he pulls up what's called a Naming Authority Pointer record that lists all the resources associated with that number, including the domain name.

Enum doesn't change the international telephone numbering plan -- which uses globally unique E.164 numbers -- or how individual countries with the oversight of the International Telecommunication Union administer these numbers. Instead, Enum lets an end user or application see what Internet resources are available for a particular telephone number. Enum is designed for use in the Internet and in private telephone numbering systems and IP networks.

On the Internet, businesses and consumers will have to pay to register their phone numbers for Enum services. The businesses and consumers can then specify their preferences for receiving incoming messages to that number, whether as live calls, voice mails, e-mails or faxes.

VeriSign sees a potential opportunity to serve as the central registry for Enum, says Pat Conley, a business development executive.

That's why VeriSign and Telcordia are hosting a free test bed for Enum developers that will run for six months starting in December.

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