T-Mobile appears to quietly be testing Enhanced Voice Services (EVS), a next-generation technology at the heart of Full HD Voice, in a move that likely is geared toward improving the quality of the carrier's VoLTE calls.
A successor of the current mobile HD voice codec AMR-WB, EVS uses complex speech compression algorithms and was designed to provide higher-quality audio than is currently available over cellular networks. EVS has been standardized by the 3GPP and will enable HD voice services to "gain even crisper and more natural voice quality in any kind of communication environment," according to a 2014 white paper from Ericsson.
A Reddit thread from last month links to what appears to be a screen shot of engineering settings on the LG G5 showing T-Mobile support for the new technology. The G5 launched through T-Mobile and other major U.S. carriers last week.
The screen shot was cited last week in a tweet by Milan Milanovic. A T-Mobile representative declined to comment on the matter.
The nation's third largest carrier has aggressively pursued VoLTE, so it's not surprising that it's already testing EVS. Forty percent of its voice calls are delivered through its LTE network, CTO Neville Ray said in January, and several weeks ago the carrier credited its ongoing VoLTE deployment with helping to stabilize churn.
EVS was developed through a collaboration of manufacturers, operators and technology developers, according to VoiceAge, which supplies speech and audio codecs. It's compatible with current VoLTE implementations and enables operators to reduce the bandwidth required for voice without degrading service quality compared to current narrowband or HD voice services. Like HD Voice, it generally only works between callers with devices that can use the technology.
"Envisioned use cases for enhanced voice service include improved classical telco-grade telephony, and high-quality multi-party conferencing or audio-visual communication," according to VoiceAge, "offering a 'being-there' quality of experience. Even streaming voice and audio as well as offline voice and audio delivery are possible application scenarios."
The G5 appears to be the first T-Mobile handset to support EVS, but it may not be the only one. T-Mobile pushed a software update earlier this week to the new Samsung Galaxy S7 and S7 edge that reportedly includes "enhanced voice services," although it's unclear whether the term refers to the codec itself or simply to minor technical improvements to voice quality.
- see this Ericsson white paper (pdf)
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Article updated April 5 to credit Milan Milanovic.