AT&T's Rinne: Carriers Working on VoLTE Interoperability

Dan Jones
News Analysis
Dan Jones, Mobile Editor
9/9/2014



LAS VEGAS -- Super Mobility Week -- AT&T's Kris Rinne says that the carrier is working with several other operators on enabling direct voice-over-LTE calls between their networks.

Rinne, senior vice president of network and product planning at AT&T Inc. (NYSE: T), was nominally at the re-branded CTIA show to talk in her role as the chairperson of the 4G Americas board of governors -- of which, more later. It seemed like a good opportunity, however, to ask a little about AT&T's VoLTE progress.

Particularly as Apple Inc. (Nasdaq: AAPL) has just unveiled the iPhone 6 with VoLTE onboard. Samsung Corp. 's Galaxy S5 is one of the devices that already has the 4G voice capability, Rinne noted. (See Apple's New iPhones Have 20 LTE Bands, VoLTE).

"We've already got several compatible devices available already, and more coming for the holidays," Rinne says.


Want to know more about machine-to-machine (M2M) communications? Check out Light Reading's dedicated VoLTE channel.


AT&T said in May that it is launching VoLTE in selected areas of Illinois, Indiana, Minnesota and Wisconsin. "We primarily started in the Chicago area," Rinne tells Light Reading.

AT&T is taking a market-by-market upgrade approach with VoLTE. "We can do that because we have handover capabilities with the UMTS network," she says.

What she means is that GSM-based carriers such as AT&T and T-Mobile US Inc. are able to use a newer feature of LTE called single-radio voice call continuity (eSRVCC) that allows users to move between VoLTE and a 2G/3G connection without dropping the call. Rival Verizon Wireless is instead doing a VoLTE launch across its full 4G footprint, because eSRVCC isn't available for CDMA-based networks.

Nonetheless, AT&T still has to do work with each LTE market to ensure it can support VoLTE. Rinne explains that, in particular, in today's LTE network the download rates tend to much higher than the upload rates. "In a VoLTE environment that needs to be symmetrical," she notes. The operator is adding in e911 emergency call support as it moves between markets.

VoLTE will also require a raft of new interoperability work, because without SIP trunking agreements and other tweaks, you can't make VoLTE calls to other operators' networks right now. Rinne says that AT&T is doing "lab-to-lab tests" on VoLTE interoperation right now with several operators. She states that such interoperability will benefit the whole industry.

"That is something that we're working across the industry on -- getting that all-IP interoperability."

VoLTE is further on at AT&T than multicast video at the moment. eMBMS (evolved Multimedia Broadcast Multicast Services) -- also known as multicast or broadcast LTE -- allows an operator to stream video to many more users than the network can support today.

Sixteen or more operators are testing multicast now. Verizon is expecting to launch sometime in 2015. (See GSA: 16 Operators Trial LTE Multicast and Verizon's Multicast LTE Video to Arrive in 2015.)

"We've been doing some technology evaluation in that regard," Rinne says. "That's a 2015 or 2015-plus timeframe for us."

So, Rinne is not going to be the one spearheading that work, as she has with much of AT&T's LTE development so far and network upgrades before that. It was recently confirmed that Rinne plans to retire at the end of November. (See AT&T's Kris Rinne to Retire.)

She tells us that she isn't planning to look for another role in tech after she leaves AT&T: "I already have the best job." she says.

"I really hope to be able to take some of the technology and management skills Iíve learned at AT&T and use them to help give back to the community and my church," she tells Light Reading.

— Dan Jones, Mobile Editor, Light Reading

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