T-Mobile US jumps on VoLTE train, launches service in Seattle

T-Mobile US got in on the recent voice over LTE fun, announcing today that it has launched the data-based voice service in the Seattle area.
T-Mobile US CTO Neville Ray explained in a blog post that the VoLTE service allows for call set-up times twice as fast as traditional circuit-switched calls and the ability to simultaneously talk and access data services. In a move to one-up its rivals, Ray said T-Mobile US had also deployed Enhanced Single Radio Voice Call Continuity, which maintains a call if a customer moves from an LTE coverage area to its 3G or 2G network.
For its service, T-Mobile US said customers can currently access the enhanced offering using the LG G Flex, Samsung Galaxy Note 3 or Galaxy Light smartphones. To take full advantage of the VoLTE service, callers on both ends will need one of those devices updated with the latest software and be in an area where VoLTE is available.

In addition to transmitting voice traffic over its LTE network, T-Mobile US said the service also included HD Voice enhancements, which the carrier initially launched across its HSPA-based network last year.
Ray added that the carrier’s VoLTE launch followed that of recently acquired MetroPCS, which was the first domestic operator to launch the service across the Dallas/Fort Worth, Texas area in mid-2012.
The announcement comes on the heels of larger rivals AT&T Mobility and Verizon Wireless touting their own VoLTE launch plans scheduled for the coming months. AT&T Mobility said it plans to launch VoLTE in the coming weeks across a handful of markets in Illinois, Indiana, Minnesota and Wisconsin. Verizon Wireless is planning a nationwide VoLTE launch later this year.
Sprint has been quiet on the VoLTE front, with an executive at the recent Competitive Carriers Association event telling an audience that the carrier’s current CDMA network’s voice delivery running the 1x-Advanced standard is comparable to VoLTE in terms of spectral efficiency, and that in the near term Sprint is more focused on voice-over-Wi-Fi than on VoLTE. Ron Marquardt, VP of technology at Sprint, said that with 80% of network traffic already moving over Wi-Fi networks, voice-over-WiFi is the next logical step. He said that Sprint will eventually move to an all-IP voice network, but that this goal is far in the future.
“CDMA is going to die, but not anytime soon,” Marquardt said, adding that the carrier has invested heavily in the technology, and retiring it in the near term would be “an accounting nightmare.”
VoLTE deployments have been hampered by technical challenges, including call quality and power management. Analysts have noted that unlike regular data transmissions, packet loss during a voice call could lead to unacceptable call quality for consumers that have become accustomed to the fairly stable call quality provided by digital circuit-switched networks.
Doug Makishima, COO at D2 Technologies, recently touched on the power management challenges of VoLTE in a RCR Wireless News Reality Check column. Makishima explained that VoLTE tests conducted by Metrio Wireless in early 2013 “found that a 10-minute call made over a CDMA network used 680 mW power as compared to a VoLTE call, which needed 1,368 mW.” However, chip vendors countered those claims by stating significant progress had been made in managing power consumption.
The ability for VoLTE calls to fall back to a 2G or 3G network has also stymied deployments as most LTE deployments currently lack the geographical coverage of legacy systems. Most equipment vendors and carriers are looking at a circuit-switched fallback solution to allow for calls to be maintained when switching between network technologies.
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