Feature Article

April 05, 2012

Yes, Sprint Introduces (CDMA) HD Voice, But -

Yes, Sprint officially announced it will be supporting HD voice on its shiny new HTC EVO 4G LTE phone. And yes, Sprint will be supporting HD voice in “late 2012.” And yes, Sprint is the first carrier on the planet to announce it will deliver HD voice NOT via voice over LTE (VoLTE), but using Qualcomm 3G CDMA 1X Advanced technology and EVRC-NW codec.  

One of the big questions standing out in my head is how/if/will Sprint transcode between a Qualcomm 3G 1X Advanced (can we just call it 1X?) HD voice handset and a VoLTE one. Sprint has until at least 2013 to figure this out, when it plans to support VoLTE. The native codec for VoLTE is AMR-WB, the de facto standard for HD voice in the 3G HSPA world while Qualcomm’s HD voice codec covers, well, Qualcomm’s 1X world.

If you are going to offer/promote/hype an HD voice experience, one would assume you would be able to transcode between the 1X EVRC-NW codec world and the VoLTE/HSPA AMR-WB codec world. Otherwise, you have to dumb-down the phone call on the shiny new HTC EVO 4G LTE phone to narrowband, thereby killing all the glory and wonder brought to the mobile experience by HD voice.

So, the first question waiting for Sprint is: How and when will you support HD voice transcoding between 1X and the lands of the AMR-WB? (Answers such as, “Look at how shiny the new HTC phone is” are not valid.)

Question two: Who other than Sprint will support 1X Advanced HD voice calls? Qualcomm has previously suggested 1X Advanced phones are seeding (going into) in markets around the world, with carriers in all regions deploying 1X advanced. Sprint says more phones supporting (presumably 1X Advanced) HD voice are coming throughout the year and EVRC-NW will be a part of every chip shipped from Qualcomm moving forward.

For the U.S. market, the question becomes simple: Will Verizon Wireless support 1X Advanced on its 3G network? 

Yes, it’s very cool that Sprint is supporting HD voice over CDMA but Sprint also supported WiMAX and look where that ended up. Sprint doesn’t want to be the mobile world’s Island of Misfit Technology Toys.   Leap Wireless is deploying 1X Advanced, but it is apparently leveraging the technology to free up spectrum, rather than delivering HD voice service. Verizon Wireless appears to be all-in on LTE, so there’s no help there.

The final question rolls into how the HTC EVO 4G LTE and other new 1X Advanced phones will handle voice calls – especially HD voice calls – when devices roam between 3G and LTE networks. Will new Sprint phones be able to seamlessly move calls between 3G and LTE networks using a single radio (Single Radio Voice Call Continuity or SRVCC)?

I suspect the answer the answer is “Yes,” given Qualcomm boasting about SRVCC prior to and during Mobile World Congress 2012. SVRCC is important because it keeps the cost of devices down (fewer parts) and translates to longer battery life over a phone that needs to keep two radios up and running when switching between calls.

Regardless of the answers, Sprint has fired a very public shot across the bow of AT&T, T-Mobile USA and Verizon Wireless. It will be interesting to see how the other major North American carriers respond between now and at CTIA next month.

Edited by Jennifer Russell

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