Report: AT&T's VoLTE-based HD Voice exceeds 3G voice, Skype in terms of quality

AT&T Mobility's (NYSE: T) Voice over LTE-powered HD Voice solution provides much better call quality than traditional circuit-switched fallback voice or voice service from an over-the-top application, according to a new research report.

The report, from Signals Research Group, is based on a multi-day evaluation of the AT&T deployment of VoLTE-based HD Voice in Minneapolis-St. Paul, Minn., using equipment from Spirent Communications and others. The tests were conducted in mid-June with some subsequent tests taking place in mid-July.

In May AT&T launched the service in select areas in Illinois, Indiana, Minnesota and Wisconsin, and said it would expand to additional markets later, though it has not indicated when it will do so.

Alcatel-Lucent (NYSE: ALU) is the infrastructure vendor for AT&T in the Minneapolis market, supporting the radio access network, the core network and IMS, including the primary VoLTE functionality. AT&T loaned Signals Research two Samsung Galaxy S4 mini smartphones but otherwise had no involvement in the study.

According to the report, Signals Research concluded that "VoLTE is pretty much everything that we hoped it would be."

The study found that call quality on the VoLTE system "greatly exceeded" that of 3G circuit-switched fallback voice "and it was measurably higher than Skype Voice," the OTT voice application that was tested. The tests included network loading, background applications running on phone and data transfers, and found that VoLTE calls were not impacted but the Skype Voice calls "frequently failed to deliver the voice packets," the report said.

In terms of how VoLTE compares to 3G circuit-switched voice, the study found that VoLTE's "other big advantage was the call setup time." A circuit-switched call took nearly twice as long to set up as a VoLTE call, the report said.

Further, the report found that VoLTE requires much fewer network resources than Skype and presumably other OTT voice apps, and VoLTE calls also required less battery power. The report concluded that "continued improvements in LTE network coverage will give VoLTE an even greater advantage in the future," including fewer handovers to 3G networks using Enhanced Single Radio Voice Call Continuity (eSRVCC).

The report's findings, though based on a single market over a relatively short period of time, could bolster the case for a quicker move to VoLTE and away from 3G-based voice services. AT&T rival Verizon Wireless (NYSE: VZ) has taken its time in deploying a nationwide VoLTE solution because of concerns that its VoLTE service needs to be just as reliable as its CDMA voice network. The carrier has said it is working to densify its network in order to properly address VoLTE handoffs. Verizon plans to launch VoLTE near the end of this year on a nationwide basis, rather than via a market-by-market approach.

For its part, T-Mobile US (NYSE:TMUS) recently said it now has 200 million POPs covered with Voice over LTE technology on it network, though it doesn't sell many VoLTE-capable phones yet. Sprint (NYSE: S) has not yet given a timetable for when it will launch VoLTE, though there are rumors it may do so in the first half of 2015.

For more:
- see this report (PDF)

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