IETF could propel Web 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 on-line telephony services.

The Internet Engineering Task Force (IETF) published its Enum specification as a proposed standard in September. Last month, Telcordia Technologies Inc. and VeriSign Inc. announced the first large-scale test of Enum services. And network vendors such as Cisco Systems Inc., Lucent Technologies Inc. and Nortel Networks Corp. 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.,” said 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, said 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.

“There are 250 million telephones in the U.S. If 1 per cent of those numbers were registered as Enum records, that would be 2.5 million registrations,” Conley said. “We think [Enum] could be a big opportunity around the globe.”

Enum developers say the technology will be useful in an array of corporate applications, including e-mail, instant messaging and voice-over-IP services.

“Enum would be supported in Web browsers, e-mail clients and voice mail systems for unified messaging scenarios,” said Patrik Faltstrom, author of the Enum specification and a Cisco engineer. “You could have a system that, at the voice prompt, records a message and sends it on as e-mail.”

In conjunction with another IETF protocol-Voice Profile for Internet Messaging-Enum would let carrier and enterprise voice mail servers locate each other over the ‘net and exchange messages. Enum also would let Internet-aware fax machines send documents to each other and to unified messaging systems.

But Enum shows the most promise in making it simple to place telephone calls over the Internet.

“What Enum does is allow [voice-over-IP] proxies and gatekeepers to find each other with no other information than the phone number,” said Richard Shockey, co-chair of the IETF’s Telephone Number Mapping group and a senior technical industry liaison with NeuStar Inc., the North American telephone numbering authority. “That’s always been the biggest problem in [voice-over-IP] services.”

This innovation promises big savings for corporations, which typically spend 40 per cent of their long-distance bills on internal communications, Shockey said.

“Voice over IP. Universal messaging. Fax. These are major enterprise applications that can be enabled more efficiently over IP networks vs. switched networks,” Shockey added. “Enum leverages the enormous investment that corporations have made in their IP backbones and VPNs.”

One application that already supports Enum is Bind 9, the latest version of the open source software that powers most DNS servers. Bind 9 supports all the resource record types required by Enum, said David Conrad, chief technology officer at Nominum, which wrote Bind 9.

Although the Enum protocol is considered solid, it faces a slew of administrative and regulatory hurdles before it can be deployed in the U.S. One challenge was resolved one week ago, when the Internet Assigned Numbers Authority set aside a new the storage of E.164 numbers.

The next question is: Which federal agency will oversee Enum registrations? Telephone numbering administration is handled by the Federal Communications Commission, while the U.S. Department of Commerce oversees DNS. Some regulatory agency will need to oversee Enum subdelegations.

Another sticky issue is the ownership and portability of Enum registrations. Businesses and consumers don’t own their telephone numbers, but they do own their domain names and can move them from one ISP to another.

“The technology is pretty much there. It’s just a matter of setting up the administrative infrastructure and procedures you need to make it work,” said Penn Pfautz, an AT&T Corp. manager and a participant of the IETF Enum effort.