T-Mobile activated Voice over LTE (VoLTE) in the Seattle area for customers using LG G Flex and Samsung Galaxy Note 3 and Galaxy Light devices.
In a blog post, Neville Ray, Chief Technology Officer at T-Mobile, said the rollout uses Enhanced Single Radio Voice Call Continuity (eSRVCC), a new LTE Advanced function. T-Mobile is the first to deploy it in the U.S.
T-Mobile is working on rolling out VoLTE in other markets nationwide. It also plans to launch a host of rich communication services and additional innovations around Wi-Fi calling over the coming months.
He also noted that MetroPCS was the first to launch VoLTE in the U.S. back in 2012.
http://multimediacapsule.thomsonone.com/t-mobileusa/t-mobile-brings-voice-over-lte-to-seattle