VoEx raised Global Crossing's status to its "carrier of choice" among 20 other providers due its more modern version of voice over Internet Protocol ( ) that lets voice calls travel using more efficient IP means rather than traditional phone signaling. Most of VoEx's other carrier partners don't use so-called pure VoIP. Many still rely on older, more expensive, and less efficient telephone technology to handle the tricky task of handing off calls between networks.
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"When we tried to hand off that call to AT&T, for example, there would be multiple times when it would have to be switched from IP to the regular phone network," he said. "The more you do that, the more times signals don't carry through. Voice calls are impaired, and data tied to that call is lost or impaired."
A small but growing number of carriers like VoEx are opting for pure VoIP for those same reasons. But for now, most VoIP service companies that also own their own networks have settled on time-tested telephone circuit switches to ensure the handoff of voice calls isn't fumbled, rather than use the new class of VoIP equipment that manages the same safe passage for about 20 percent less cost.
Time Warner Cable is one such example. Itto ensure VoIP calls can reach what's known as the public switched telephone network. Mark Chall, Sprint director of service deployment, said last month after the deal was announced that Sprint will use traditional phone equipment to guarantee the passage of Time Warner Cable calls onto its own network and vice versa.
The problem, however, lies in the basic protocols used to signal VoIP connections, session initiation protocol and H.323. It's an evolving standard that has been implemented differently by equipment makers. As a result, soft switches and IP 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.