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T-Mobile, AT&T Launching VoLTE Service

Bellevue, Wash. — T-Mobile launched Voice over LTE (VoLTE) service with HD Voice in Seattle and plans to expand the service to other markets throughout the year on a schedule that it didn’t reveal.

Three handsets — the LG G Flex, Samsung Galaxy Note 3 and Galaxy Light — will support the service after users download a software update.

On May 23, AT&T plans to launch Volte with HD Voice in select areas in Illinois, Indiana, Minnesota and Wisconsin with plans to add additional markets at unspecified later dates. Only one AT&T-network phone — the Samsung Galaxy S4 Mini — will support VoLTE and HD Voice at launch.

For its part, Verizon plans to launch Volte with HD Voice nationwide sometime this year. Sprint hasn’t unveiled a timetable to launch VoLTE or HD Voice over VoLTE.

In areas with VoLTE service, LTE-equipped phones send voice calls as IP packets over LTE data channels to conserve spectrum and increase network capacity. VoLTE calls can be made to any handset even if it lacks VoLTE technology.

A VoLTE advantage that more directly affects consumers is faster call setup times, almost twice as fast as the setup times of non-VoLTE calls, said T-Mobile chief technology officer Neville Ray. Users will continue to enjoy high-speed LTE data sessions while on a call.

With HD Voice over VoLTE, consumers enjoy clearer voice quality and reduced background noise, AT&T said. HD Voice uses wide-band audio technology and noise cancellation to make voices sound more natural compared to standard voice calls, the carrier said.

To enjoy HD Voice benefits, both caller and receiver need an HD Voice-capable phone and must be located in an HD Voice coverage area, AT&T noted.

In launching HD Voice over VoLTE, T-Mobile said it will be the first carrier to use Enhanced Single Radio Voice Call Continuity (eSRVCC) technology that “helps ensure that your capable phone won’t drop a call if you leave an LTE area and it switches to 4G HSPA+ or 2G coverage,” Ray said.

Potentially, VoLTE could be used to offer a host of so-called Rich Communications Services (RCS).In fact, said Ray, “launching VoLTE is our first step toward a host of rich communication services and additional innovations around Wi-Fi calling that we’re looking to deliver to our customers over the coming months.”

RCS integrates basic voice and messaging with such services as instant messaging, Wi-Fi calling, video calling and content sharing. RCS enables sharing of multimedia messages and files while on a call, and it enables instant messaging and group chat without an over-the-top app. Users also don’t need an over-the-top video-chat application to place video calls.

In other advances, RCS phones detect whether another person’s RCS phone is on, if the person is in a meeting based on their calendar status, or if the person has set a status showing they are willing to accept incoming communications.

With RCS’s Wi-Fi calling, users can place a regular voice call over Wi-Fi in areas with limited cellular coverage.

For its part, Verizon has said it plans to offer video calling along with HD Voice when it launches VoLTE.

Although Sprint hasn’t unveiled a timetable to launch VoLTE or HD Voice over VoLTE, the carrier plans to expand HD Voice over CDMA service throughout the country by the middle of this year. That service, which uses EVRC-NW technology for HD Voice, is incompatible with T-Mobile’s W-AMR-powered HD Voice on its HSPA network. T-Mobile rolled out HD Voice over HSPA+ in January 2013.