SKT Launches World’s First HD Voice over LTE
SKT Launches World’s First HD Voice over LTE
  • Kim Sung-mi (
  • 승인 2012.08.07 17:30
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SEOUL, KOREA — SK Telecom (NYSE:SKM) announced today that it will launch ‘HD Voice,’ the next generation high-quality voice call service over LTE, on August 8, 2012 for the first time in the world. 

HD Voice offers HD (high definition) sound quality by using high-quality audio codec capable of handling 2.2 times wider frequency bandwidth than that of 3G voice calls to make customers feel as if the person on the other end of the line is sitting right next to him/her. Moreover, the call connection time is less than 0.25 to 2.5 seconds, 2 to 20 times shorter than 3G voice calls that require an average of 5 seconds to connect a call. 

SK Telecom has been constantly upgrading its voice service – i.e. from analog to digital and from 2G to 3G than to 4G – for a clearer and crisper sound quality. Analog voice call back in 1984 was more like a radio walkie-talkie, giving many problems including frequent call disconnections. Then, with the introduction of a digital cellular technology called Code-Division Multiple Access (CDMA) in 1996, audio quality improved through the application of Enhanced Variable Rate Codec (EVRC)-based speech coding optimized for mobile telecommunications using 8 Kbps bandwidth. 3G Wideband Code Division Multiple Access (WCDMA) has further heightened the voice call quality through the adoption of Adapted Multi-Rate Narrow Band (AMR-NB) for speech coding and usage of 12.2 Kbps bandwidth. As a result, quality of voice call service over 3G network boasted 30% better audio quality than that of 2G.

In line with its previous efforts, SK Telecom will be launching HD Voice on August 8, 2012, the world’s first high definition voice call service over LTE that can dramatically push up audio quality. HD Voice uses Adapted Multi-Rate Wide Band (AMR-WB) codec, which offers much upgraded 3G speech coding, and 23.85 Kbps transmission bandwidth, 2.2 times wider than that of 3G voice call, thereby transmitting the previously-inaudible low and high sound waves, and improving voice quality by 40% compared to that of 3G.

HD Voice (AMR-WB) provides a much richer, clearer and more natural speech quality due to a wider speech bandwidth of 50–7000 Hz compared to 3G voice call service that is optimized for only 300–2400 Hz voice band. 

HD Voice will be provided at same rates (KRW 1.8 per second) as that of 3G under pay-per-second billing scheme and allow users to make/receive HD Voice calls without going through a subscription process, thus enabling them to conveniently experience the high-quality, premium service with no additional cost burden.

To enjoy the richer, fuller sounds of HD Voice, both people on a call will have to be subscribed to SK Telecom’s LTE service and have HD Voice-capable devices. The company will begin selling Galaxy S3 LTE embedded with HD Voice feature on August 8 and plans to offer firmware upgrades for existing users of Galaxy S3 LTE within this month. Going forward, high-quality voice call is expected to be realized among VoLTE customers of different carriers through service interworking among three Korean mobile carriers. In addition SK Telecom plans to embed HD Voice as a basic feature in most of its LTE smartphones to be released in the future. 

As an All IP-based premium service that provides high-quality voice, video and data in an integrated manner unlike traditional simple voice calls, HD Voice can be expanded to many new and value-added services. For instance, it offers both voice and video services characterized by seamless in-call voice-to-video call switching and content sharing by linking to RCS services.

SK Telecom developed and applied diverse cutting-edge technologies to offer the best possible voice quality to customers. In particular, the company secured quality stability by applying QoS Class Identifier (QCI) to its LTE network in order to handle HD Voice speech data first.

Meanwhile, SK Telecom completed nationwide LTE rollout (covering 99% of the population) by June 2012 and is providing LTE coverage in underground and in-building areas as well as mountainous region, and coastal/island/marine areas. Moreover, the company was the first in the world to commercialize core LTE technologies including Advanced-SCAN[1], LTE femtocells[2], and Multi Carrier[3] to support its high quality HD Voice.

Joon-dong Bae, President of Network Operation Business of SK Telecom said, “With the commercialization of HD Voice, SK Telecom firmly establishes itself as top LTE service provider in terms of market share, network infrastructure and technology. Going forward, SK Telecom will continue to provide customers with innovative, lifestyle-enhancing LTE services including those that utilize HD Voice.”

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