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T-Mobile, Sprint Are on the Bumpy Road to HD Voice

T-Mobile, Sprint Are on the Bumpy Road to HD Voice

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Among the many the headlines T-Mobile (DTE:GR) made last week at its un-carrier event was that its newly acquired iPhone 5 would support HD Voice, a technology that does exactly what its name implies: makes calls sound clearer and crisper.

HD Voice, however, is hardly a new technology. Operators have been experimenting with it for some time. Two carriers, T-Mobile and Sprint (S), have upgraded their networks to support HD calls. Speaking at VentureBeat’s Mobile Summit on Monday, AT&T network Senior Vice President Kris Rinne reiterated Ma Bell’s commitment to launch HD Voice over its LTE network later this year. Verizon Wireless is dallying a bit. It originally planned to launch HD Voice-capable phones on its LTE networks last year but, according to FierceWireless, Verizon is now targeting the late 2013-early 2014 time frame.

Given all that HD Voice activity, why have we heard relatively little about the technology from the carriers, apart from the occasional big-splash announcement such as T-Mobile’s? As with so many problems in the mobile industry, the reason for HD’s lackluster momentum is interoperability. Even if you own an HD Voice-capable phone on an HD Voice-compatible carrier, chances are that you’ve never made an HD Voice call.

Sprint and T-Mobile are both using different HD Voice technologies that are based on the radio standards of their respective network standards, CDMA and GSM. For a detailed explanation, ExtremeTech’s Neal Gompa has written an excellent primer on the differing HD Voice technologies and their inherent limitations. It basically boils down to this: To make an HD call, you need to meet all the following stipulations.

Your phone needs to be HD-capable. Not just HD-capable, it must support the HD Voice codec used by your carrier. In the case of T-Mobile, that means the iPhone (AAPL), the Samsung (005930:KS) Galaxy S 3, the HTC (2498:TT) One S, and probably, most newer generation smartphones. For Sprint, that does not include the iPhone because Apple isn’t supporting the CDMA HD-Voice codec, but it does include the HTC Evo 4G.

The phone you’re calling needs to be HD-capable. Not only does the recipient need an HD device, it needs to be running on an HD-compatible network that uses the same HD technology as your device. Even if Sprint and T-Mobile customers both have the right phones, they can’t make HD calls to one another. If either calls any other carrier or any wire-line number, the voice connections will revert to “standard-definition.”

Both phones need to be connected to an HD-capable base station. Just because a carrier supports HD Voice doesn’t mean it supports it in all places. Sprint, for instance is enabling it as it upgrades its CDMA systems as part of its Network Vision overhaul (basically everywhere it offers LTE). When Verizon and AT&T launch their voice-over-LTE (VoLTE) services, both caller and recipient will have to be on LTE networks for the conversation to transmit in HD. T-Mobile, however, appears to have upgraded its entire network to support HD.

As you can see, this is a pretty high bar to meet. Consequently, carriers aren’t bragging much about their HD Voice services—very few of their customers can feasibly make an HD call. We’ll start to see more activity as the growing number of iPhone and Galaxy customers on T-Mobile’s network contact one another, but we’ll see the biggest uptick in HD usage when Verizon and AT&T take their VoLTE services live.

Unlike with CDMA, there will be compatibility between VoLTE HD voice technologies and T-Mobile’s GSM-based systems because they use what is basically the same codec. As T-Mobile and Sprint  migrate to VoLTE, there will eventually be even greater interoperability.

As my GigaOM Research colleague Colin Gibbs points out, voice quality is still an important factor for consumers when they select a mobile service. It’s difficult, though, for carriers to distinguish themselves competitively with HD-Voice because adoption of the service depends on all carriers offering the technology. That said, HD Voice could boost the industry as a whole by making mobile calls more pleasant, rather than the patchy conversations they often are today.

Also from GigaOM:

CES 2012: Recap and Analysis (subscription required

Tesla, Fisker, and What Could Have Been: A Tale of Two Car Startups

For Facebook, It’s Not About Their Phone; It’s About Your Phone

Applied Micro’s Cloud Chip Is an ARM-Based, Switch-Killing Machine

‘Linux of Online Learning’ Gets Stronger; EdX and Stanford Team Up to Build an Open-Source Platform

Fitchard is a writer for the GigaOM Network.

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