South Korean service provider SK Telecom has launched HD voice call service over LTE. According to the company, HD voice 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 claims to be first to offer 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.

Operator will offer HD Voice 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.

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. 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 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.