VoLTE: So Close You Can Hear It

BARCELONA, Spain -- Mobile World Congress. Despite many false starts, the GSMA is expecting no less than 20 voice-over LTE (VoLTE) deployments this year.

The next ones are being announced this week at the GSM Association (GSMA) 's own show in Barcelona. For one, Asian operator SingTel Optus Pty. Ltd. said Monday it will launch VoLTE in Singapore "in the coming months" in partnership with Ericsson AB (Nasdaq: ERIC). The deployment will use Single Radio Voice Call Continuity (SRVCC) to kick users back to 3G where LTE is not available, and will be supported by a number of compatible Samsung Corp. phones, including the next Galaxy S, the Galaxy S4, and the Note 3 via a software upgrade.

China Mobile Ltd. (NYSE: CHL) is also expected to announce an expansion of its initial launch with ZTE in Guangzhou this week, and the carrier is showing off virtualized VoLTE with Alcatel-Lucent (NYSE: ALU) at the show. (See China Mobile, ZTE Kick Off VoLTE Rollout , Alcatel-Lucent Lays Out Its NFV Plans, and China Mobile, Alcatel-Lucent to Demo NFV at MWC14 .)

Among the US-based operators, both Verizon Wireless and AT&T Inc. (NYSE: T) have been testing VoLTE in the network and handsets, respectively, and Sprint Corp. (NYSE: S) formed a partnership with BroadSoft Inc. to manage its VoLTE migration, suggesting initial trials at least may not be far behind. (See Verizon VoLTE Testing Spotted, AT&T's VoLTE Phones Start Trickling Out , and Sprint Taps BroadSoft for VoLTE Transition.)

There have been so many fits and starts around VoLTE as operators look to build a superior service to 3G voice, but Paul Gowans, JDSU (Nasdaq: JDSU; Toronto: JDU) mobility marketing manager, told Light Reading he thinks the delays are finally over. The market is now mature enough in its understanding of the end-to-end nature of what's required, he said.

It's that end-to-end nature that's caused VoLTE to be delayed so long, too. Gowans said there have been two main challenges with VoLTE -- optimizing the radio access network (RAN) and the service quality. Service quality has to be assured from the RF level to the RAN to the device itself. The RAN causes the most issues, he said.

"If you think about it as one chain from end to end, if one piece causes a problem, the whole thing breaks down," Gowans said of the delays. Test and measurement vendors such JDSU have been engaged in finding those issues in the pre-deployment testing, to identify where the whole process typically gets hung up.

Dan Warren, the Senior Director of Technology for GSMA, added two other challenges that are still troubling operators -- the increased signaling load of VoLTE and call-recognition failures in which the phone doesn't recognize the device it's calling and permanently blocks the number. He said operators are tackling these issues now, and the GSMA is doing its part to speed up finding the answers. (See VoLTE Needs Passing Grade From Operator Tests and MW13: Tekelec Warns of VoLTE Signaling Storm.)

The industry association produced a guide, “VoLTE Service Description and Implementation Guideline,” in October to facilitate roaming relationships, as well as a launched an “internal support area where operators can share knowledge and help figure out issues between each other.

VoLTE still won't be a crystal-clear proposition as the launches do occur. As Gowans pointed out, it requires a new handset or firmware update for a lot of devices, and roaming and interoperability issues will take longer for the GSMA to wade through. Until deals are forged, a VoLTE user calling someone on a different network will still fall back to 3G. It will be a while before it lives up to its full potential.

"This year things will start to build up," Gowan said, "but it will be still building up in islands."

— Sarah Reedy, Senior Editor, Light Reading

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