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Networking

Communication breakdown threatens VoIP

Complications threaten to erupt on the back end of Internet telephony that could hold back cost savings for providers and ultimately dampen expectations for the much-hyped technology.

As cable and telephone companies begin offering Net telephony services to consumers in earnest, complications on the back end threaten to crimp cost savings for providers and ultimately dampen expectations for the much-hyped technology.

Broadband providers with dreams of nationwide voice over Internet Protocol (VoIP) services are already encountering unexpected difficulties stemming from subtle differences in the way various carriers have set up technology used to carry voice calls over the Internet, executives said this week.


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While relatively harmless if the calls remain on a single operator's labyrinth of fiber or copper, cable and phone companies are finding that the jump from one network to the next is proving to be an expensive problem.

"The lack of interoperability at a technology level and on an operational level have slowed end-to-end deployment of VoIP," said Lisa Pierce, a research fellow for Forrester Research.

The victim in the border war could be the high expectations surrounding VoIP, a cheaper way of making a phone call by using the Internet rather than traditional phone networks, which rely on less efficient and more expensive transporting methods.

Currently, about 11 percent of all phone calls use VoIP at some point in the connection, with some analysts forecasting a $10 billion a year business for broadband providers selling a majority of the world's phone calls. Most of this VoIP shuttling takes place in delivering international calls, through IP network providers such as iBasis and ITXC. Calls are handed off to traditional circuit-switched networks at either end, but make long-distance jumps using cheaper packet switching, or IP, technology.

As more calls shift to IP, these handoffs will grow in volume and complexity, raising significant technical and contractual issues for carriers, experts said.

At the technical heart of the problems are the basic protocols used to signal VoIP connections, session initiation protocol and H.232. These are evolving standards that have been implemented differently by equipment makers. As a result softswitches and Internet protocol gateways from one vendor may not interoperate with equipment from another. And if the equipment sitting on each network isn't able to talk to each other, then the call can't be completed.

"One can imagine simply taking IP traffic from one network to another," said Joe Aibinder, product marketing director for AT&T. "But there is more to it than that. You have to be using the same type of softswitch with the same software release to make the connection."

A new category of product has been developed to help alleviate this issue. VoIP session controllers can be deployed between two carrier networks to help simplify the protocol conversion. Acme Packet, Ingate Systems, Jasomi Networks, Kagoor Networks, Netrake, NexTone Communications, Ridgeway Systems and Software, and softswitch maker, Sonus, all offer session control products.

But even with session control technology translating the protocols, carriers still need to test and tweak the networks at the interconnection points.

"At this level there's always some sort of testing and certification that must happen," Aibinder said. "But it is becoming easier."

Edward Morche, vice president of soft-switch business development for Level 3 Communications agrees. Level 3, which is considered a carrier's carrier, has been interconnecting IP networks for the past four years. Most of these early deployments required a lot of customization and tweaking to allow seamless communication between networks. Just recently, the carrier has installed session controllers from Netrake and NexTone Communications to help make this process less labor intensive, so that it's able to offer the solution to more customers.

Morche said that Level 3 has been able to reduce the amount of time it takes to test network interoperability from months to a couple of weeks. "We'd like to get this down to a couple of days," he said. "But the technology and the industry are still maturing."

Other looming issues for voice hand-offs include nettlesome billing arrangements. Internet carriers that share lots of traffic currently use "peering" agreements that essentially agree to waive transport charges on the assumption that costs are generally a wash. Whether those agreements will be extended to voice traffic remains unclear, however, as carriers begin to see traditional phone tolls take a hit as VoIP volume takes up a bigger percentage of calls.

The so-called "handoff" problem includes those from the traditional telephone world, which are partnering with cable providers to ensure that their digital phone calls can reach the public switched telephone network, still used by nearly every U.S. house and business.

For now, most broadband providers peddling VoIP service have settled on a time tested telephone circuit switches to ensure the handoff of voice calls isn't fumbled, rather than new class of networking equipment that manages the same safe passage for about 20 percent less cost.

Time Warner Cable is one example. It hired Sprint Communcations and MCI to ensure VoIP calls can reach what's known as the public switched telephone network. Mark Chall, Sprint director of service deployment, said for now, Sprint will use traditional phone equipment to ensure the passage of Time Warner Cable calls onto its own network and vice versa.

"Sprint's plan is to move to a more elegant handoff," he added, "probably in the next year."