Asterisk Guru May Have Solved Interconnection Dilemna

VoIP service providers have feared connecting directly to one another for competitive reasons. Now, Mark Spencer, the developer of the Asterisk open source PBX, has a peer-to-peer module that may provide the solution. Already, a handful of providers have signed on with Spencer's DUNDI and others may soon join in.

What has been a longtime complaint of many VoIP users – the limited ability of users on separate IP networks to call each other over a direct IP-to-IP connection – may well be addressed through a new number discovery protocol developed by Mark Spencer, the lead architect behind the highly regarded open source PBX system, Asterisk.

The Distributed Universal Number Discovery, or DUNDI, says Spencer, "solves one of the holy grails of Voice over IP, direct IP connectivity."

DUNDI, says Spencer, is a "true peer-to-peer" system that allows users of disparate telephone networks to find each other at a regular phone number simply by querying tables maintained on each network's server.

Already, said Spencer, a number of commercial and free service providers have agreed to the standard, including a General Peering Agreement ("GPA") that is available on a new web sited Spencer developed for the project,

Among the service providers Spencer lists as supporting DUNDI are VoicePulse, SIPPhone, Free World Dialup, Telesthetics, Nufone and SpeakUp.

Once the providers put up complete tables of their users, including phone number, device MAC addresses and URL identifiers, a user on one service participating dialing a user on a separate participating service will be able to make a voice connection while bypassing the PSTN system.

Currently, for example, a call between a Nufone customer and a VoicePulse customer, travels over the traditional PSTN between the Nufone and VoicePulse servers.

Using DUNDI, the PSTN portion of the call is unnecessary as the caller would be able to find the recipient's phone directly via IP using peering tables.

"This is what VoIP was supposed to be about," said Spencer.

DUNDI, said Spencer, is designed to work with or apart from the DNS-based ENUM system, which maintains a centralized table of participants on a single database. "DUNDI doesn't need a central repository, such as ENUM," said Spencer. "But it can supplement ENUM by interconnecting ENUM repositories."

Spencer says the difference between ENUM and DUNDI is similar to the difference between looking up a number in a phone book and asking a friend for the right number to call.

Spencer says it will take a while before DUNDI's effectiveness can be measured. "We don't have proof that it will work, but we don't have proof that it won't work," he said. "Time will tell but I have high hopes."

Service providers have been reluctant to enter into interconnection agreements with other providers, even though such agreements would lead to lower operating costs and higher quality voice communications by bypassing the PSTN system. Interconnection agreements would require some sort of sharing of customer information, not something parties in the highly competitive VoIP environment were willing to do.

By allowing participants to store there own database of users, and not requiring the information in the database to be shared, DUNDI helps overcome the main objection.

Jeff Pulver, of Free World Dialup, was quick to embrace DUNDI. "No matter how established you get, you must be aware that disruption will happen," Pulver said. "DUNDI is disruptive and we support it."