In search of a voice-over-LTE standard

Jessica Scarpati
01 Dec 2009

Wireless carriers developing their next-generation networks using Long-Term Evolution (LTE) technology don't seem deterred that the technology is outpacing LTE standards -- probably because data over Internet Protocol (IP) packet switching isn't a major upset at this point. But defining a voice-over-LTE standard has been increasingly vital and problematic for carriers.

"It's far more critical now than it probably ever was [to use standards for voice] because far more people have a higher expectation of what mobiles do and what they expect mobiles to do. That makes it a bigger issue than maybe it would've been 15 years ago," said Steven Hartley, a principal analyst at Ovum. "You can roam with voice internationally and connect with people on other networks -- all of those things have to happen."

Six wireless operators and six vendors from across the globe recently gave their blessing to IP Multimedia Subsystem (IMS) as the LTE standard for voice and Short Message Service (SMS) to the 3rd Generation Partnership Project (3GPP), the telecom association that will ratify LTE standards. Carriers on the list included AT&T, Verizon Wireless, Orange, Telefonica, TeliaSonera and Vodafone.

If approved by 3GPP, the "One Voice Initiative" agreement would make IMS the standard for network vendors, service providers and handset manufacturers to offer compatible LTE voice solutions. It would change transport of voice and SMS, which have traditionally been sent over circuit connections, to a costly IP-based system, Hartley said.

Competition for the LTE voice standard comes from Voice over LTE via Generic Access (VoLGA), a standard pushed most visibly by T-Mobile, and circuit-switched fallback solutions.

"The fact that you've got the big hitters … behind One Voice is probably a major clue as to where things will go," Hartley said.

Even advocates of LTE standards-based solutions said they were surprised at the breadth of One Voice support. Getting major carriers and manufacturers to agree on standards is usually a long and painful process, according to Brian Wood, vice president of marketing at Continuous Computing, a San Diego-based systems provider for network equipment providers.

"It's kind of like working out a piece of legislation in Congress. There's a lot of horse trading, and usually that means things take a long time and you end with something in which nobody is delighted and everybody feels they didn't quite get everything they wanted," Wood said. "Here, the surprising thing is that so many have come together so quickly to decide on one thing, and it really clears the path."

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