Ready for Voice over LTE?

As Skype and Apple's FaceTime continue to improve the quality of calls through their services, both casual users and the world's highly skilled engineers have issued a clarion call to improve the plain old telephone.

And over the last two years, telecoms providers have responded - sort of.

For example, they have rolled out the widely touted HD Voice service.

That solution did improve call quality on same-network calls, but it suffered from interoperability issues between networks and devices.

Now, telecoms experts say the real answer to users' calls for better phone quality lies in Voice over LTE (VoLTE).

In Germany, the service is gradually being rolled out with an eye towards national service by next year.

Telephone quality today "utilitarian" at best

HP Baumeister, an expert in phone codecs at the San Jose California branch of Germany's Fraunhofer Institute, doesn't mince words when asked about what he thinks of today's mobile and fixed-line voice networks.

"The quality is utilitarian at best," Baumeister says. "It's not what we can have or what we should have."

And he should know - the Fraunhofer Institute invented the MP3 as well as the codec used in Apple's FaceTime.

Baumeister says phone companies should offer service on a par with - or better than - free, over-the-top, voice over IP providers, such as FaceTime and Skype.

"Calls should sound like streaming audio. Just like television audio quality or DVD audio," says Baumeister. "If companies were to use the very latest codecs, they could very easily achieve those quality levels."

While phone companies have talked for years about improving call quality, Baumeister says the industry has finally begun to align around the 3GPP EVS codec standard.

Gaining alignment was no small feat, says Dan Warren of the GSMA global mobile industry trade group.

"You have 800 mobile networks in the world and probably as many fixed-line providers," says Warren. "Compare that to Skype, where the codec being used is entirely under the control of one entity."

Warren says the new codec will be able to offer high definition quality because it will use 9.6-13 kilobits per second of data, rather than the 6-7 kilobits per second that most codecs currently use.

Improved interoperability

What's more, because the new standard is based on Internet Protocol (IP), it should reduce the number of cross network and device interoperability issues that have hampered HD Voice.

HP Baumeister says the industry agrees that it has to do away with today's standard - the AMR codec - which he calls a "dinosaur" not suitable for today's high fidelity world.

"The AMR codec just cannot cope," Baumeister says. "Music is terrible through AMR. Anything that's not voice is terrible. Even unusual voices and children's voices and some languages are very poorly handled."

Phone quality especially relevant in China

Patrick Callier, a linguist at Stanford University, notes that poor phone quality is especially problematic in China, where most people speak Mandarin, a tonal language.

"Languages that use tone need information about the pitch at which people are talking," Callier explains. "The pitch of the human voice generally ranges from 50-250 Hertz. The traditional narrow band phone range starts at 300 Hertz, which is above most people's normal speaking pitch. You have these tonal languages, like Mandarin, which use pitch to distinguish one word from another. And the ordinary narrow band systems will just filter that right out."

For this reason, Callier says, China is following the telecoms codec debate closely.

"It's coming up as an issue in China because it's the first tonal language among the world languages to have all those systems engineered for it," says Callier.

On the industry side, there does seem to be a commitment to creating a new standard around Voice over LTE that will meld the call quality of FaceTime with the convenience of the plain old phone.

Dirk Ellenbeck of Vodafone Germany says the industry vows to get interoperability right this time.

"The network providers are definitely working closely together to assure there's interoperability," Ellenbeck says. "The goal is to make it possible for the highest number of people to talk to each other while getting the highest possible call quality - and not just on one provider's network. We think that making it possible for our customers to talk to people on other providers will improve the overall experience."

Ellenbeck says to expect Vodafone Germany to roll out the Voice over LTE service nationally by next summer.

Meanwhile, US telecoms firms AT&T and Verizon have agreed to work together to offer VoLTE calling to and from each company's respective network by next year.