Leading with, "We're an Internet company" argument, T-Mobile US is raising the stakes again for U.S. Voice over LTE (VoLTE) deployment.  Yesterday, T-Mobile announced it now has VoLTE deployed to more than 100 million people in 15 total markets.  It expects to deploy VoLTE nationwide by the end of the year.

“The old telecoms designed their networks for a time when your phone’s only app was a phone call—and they haven’t shaken that dial-tone mind-set,” said Neville Ray, chief technology officer for T-Mobile in a company press release. “Our 4G LTE network was built in the last year and a half, so naturally we built it differently.  We built it for the way people use smartphones and tablets today, and we built it with a mobile Internet architecture, so we could roll out new technologies faster.”

VoLTE is—well, it should be—nothing more than another application running on a data network, except with some Quality of Service (QoS) thrown in to make sure voice bits get priority over someone's Excel spreadsheet.    New VoLTE deployments announced yesterday include Atlanta, Austin, Boston, Chicago, Dallas, Houston, Long Island, Los Angeles, Minneapolis, New Jersey, New York City, Philadelphia, San Francisco, and Washington DC.

T-Mobile is making the case its VoLTE and HD voice service is better because the carrier is dedicating 24 Kbps to VoLTE calls using the AMR-WB codec for the "highest fidelity" possible.  It will be interesting to see third-party apples-to-apples comparisons for VoLTE between AT&T and T-Mobile, since both carriers have announced service in Chicago and Minneapolis.    

Apples-to-oranges comparison between T-Mobile and Sprint's HD voice service will also be interesting.  Sprint is using its 3G CDMA network with Qualcomm's EVRC-NW codec to delivery HD voice, with a promise of nationwide coverage by the end of the year. Both call quality and call setup times will be benchmarks when the inevitable stories are written.

The chant of "We're a data network" also opens the door to further VoLTE improvements in short order, depending on how well-engineered the network is and the ability to load new applications. Fraunhofer has been touting its "Full HD Voice" AAC-ELD codec for over two years and ETSI is trying to formalize the Enhanced Voice Services (EVS) codec to go beyond AMR-WB , with specifications set later this year.

EVS uses anywhere between 5.9 Kbps to 128 Kbps and is specifically designed to have an AMR-WB interoperability mode (No transcoding) and work with VoLTE. T-Mobile could choose to rapidly deploy EVS on its network in 2015 to provide a superior "Superwideband" speech experience along with backwards compatibility with AMR-WB.   The company has already demonstrated the ability to outrun AT&T and Verizon in deploying both HD voice and VoLTE.

In comparison, AT&T has deployed VoLTE in four markets, Verizon is still at zero (0) at this time with a promise of something by end of year, and Sprint is "We're not talking about it much."  Softbank may be tempted to merge T-Mobile and Sprint, but it is difficult to believe that T-Mobile's competitiveness and innovation would be easily transferred over to Sprint, given the latter company's network and established corporate culture.