Voice over LTE (VoLTE) service is commercially available now. U.S. Carrier MetroPCS and South Korea's SK Telecom announced the launch of VoLTE service on Aug 8 earlier this week.  SK Telecom highlighted that 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.

Both operators also announced VoLTE capable smartphones as well. SK Telecom has launched VoLTE service with HD Voice-compatible Galaxy S3 LTE today and will offer firmware upgrades for existing users of Galaxy S3 LTE within this month. MetroPCS is selling VoLTE-capable LG Connect 4G at one of the company's Dallas/Fort Worth store locations and at select U.S. stores. It plans to continue to roll out VoLTE services and phones in the coming weeks.

SK Telecom's 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.

Since launch of LTE, voice over LTE had been hot topic as multiple options existed. VoLGA was initially much talked about but did not find the much favor from operators. Operator preferred 3GPP based CSFB and IMS based voice solution instead. VOLTE requires IP Multimedia Subsystem (IMS) technology in core network while LTE network provides access.

CSFB has helped on voice support during initial deployment of LTE across the globe and now operators are getting ready for VoLTE debut. CSFB is suitable for use when the LTE coverage does not match operators existing 2G/3G footprints and helps in the early phases of LTE deployment, while VoLTE can be implemented when the coverage is better and LTE networks become matured.

In February 2010, GSMA had adopted the work of the One Voice Initiative to drive the global mobile industry towards a standard way of delivering voice and messaging services for LTE. The GSMA’s Voice over LTE (VoLTE) initiative received backing of more than 40 organizations from across the mobile ecosystem, including many of the world’s leading mobile operators, handset manufacturers and equipment vendors, all of whom supported the principle of a single, IMS-based voice solution for next-generation Mobile Broadband networks.