The second-largest wireless carrier in the United States, AT&T, is on the cusp of rolling out what could eventually mark a strategic differentiator: high definition (HD) voice. The telecom giant is tapping its all-IP Voice over LTE (VoLTE) network as it brings its HD Voice to select markets, making it the first carrier to deploy VoLTE for high definition service.

HD Voice is a wideband technology that promises crisp call quality with reduced background noise so a caller feels like he's right next to the person on the other line. Historically, voice calls have been transmitted on a limited frequency of 300 Hz to 3.4 kHz. To provide better call quality, HD Voice greatly expands that range from 50 Hz to 7 kHz -- and even higher -- to bring high definition calling to the handset.

Limited Market To Start

With its rollout, AT&T is making a bold promise: Customers don’t have to choose between faster data Relevant Products/Services speeds and clear voice quality. HD Voice promises to let you talk while surfing the Web at 4G LTE speeds with no compromise in terms of data speed or voice quality.

However, to get the benefit of HD Voice, AT&T indicates both the caller and receiver need an AT&T HD Voice capable phone and must be located in an AT&T HD Voice coverage area. For now, that means an extremely limited market.

HD Voice from AT&T will initially be available in select areas of the U.S., in Illinois, Indiana, Minnesota and Wisconsin, starting May 23. The company said it will continue expanding on a market-by-market basis.

The Samsung Galaxy S4 mini will be the first device to include HD Voice capabilities. AT&T promised to serve the much-anticipated technology to other devices soon.

Early Advantage

We caught up with Jeff Kagan, an independent technology analyst, to get his take on AT&T’s HD Voice service rollout. He told us the announcement marks the beginning of what so many have been anxiously anticipating.

“We are expecting all the majors to offer this service sooner or later. AT&T appears to be the first to market,” Kagan said. “High definition voice will be very important going forward on all-IP, Voice Over LTE. It lets customers talk and surf the Web at high speeds at the same time over an Internet or IP network.”

Competitor Verizon Wireless plans to roll out HD Voice sometime this year, while Sprint has also been moving quickly in the meantime with its own high-definition voice technology.

Sprint's HD Solution

Late last year, Sprint demonstrated what it hoped would be its own competitive differentiator -- technology that delivers 1 gigabit per second (Gbps) over-the-air speed and has the potential to surpass wireless speeds of any U.S. network provider -- at least for now.

Dubbed Sprint Spark, the super-high-speed capability demonstrates 50 megabits to 60 megabits per second peak speeds today with increasing speed potential over time. Given Sprint’s spectrum and technology assets, the company said it is technically feasible to deliver more than 2Gbps per second of over-the-air speed. The service started rolling out in March in 100 of America’s largest cities.

“Sprint Spark will also offer high definition voice. This is supposedly a much higher quality voice call than traditional wireless,” Kagan said. “So could Sprint actually break out their old advertising from the early 1990s with the pin drop to illustrate the excellent quality? True, that was for wireline and this is now for wireless, but they can update it, can’t they?”

This article was corrected to reflect that AT&T is the first deploying a VoLTE network to provide high definition voice service -- but not the first to offer HD Voice in general.