VoLTE/Rich communications

AT&T Waits for VoLTE for Voice Roaming

AT&T is warning the FCC it may have to wait until it has voice-over-LTE (VoLTE) fully deployed to begin offering voice roaming to CDMA operators over its 700MHz spectrum.

Joseph Marx, assistant vice president of AT&T Inc. (NYSE: T)'s services division, clarified comments made on a conference call last week in a note to the Federal Communications Commission (FCC) 's Wireless Telecommunications Bureau. He was specifically addressing a statement AT&T made that "it may be necessary for some operators to wait until Voice over LTE (VoLTE) roaming is available before operationalizing LTE data roaming."

Marx writes:

    For CDMA operators, we would be able to support LTE Data Roaming but since voice is handled on the 2G CDMA network, there is no opportunity for AT&T to offer voice roaming until we support VoLTE. The staff also asked about SMS Texting while roaming on LTE data only and at this point it isn't clear that we'd be able to support SMS while roaming on the LTE data network.

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AT&T currently has VoLTE deployed in parts of about 20 states and is working toward a nationwide footprint to match both Verizon Wireless and T-Mobile US Inc. , but hasn't put a timeline on its deployments yet. It has said it's also working with Verizon to achieve interoperability between one another's VoLTE services this year as well. (See AT&T Promises More VoLTE Markets in 2015 and Verizon, AT&T Plan VoLTE Harmony in 2015.)

AT&T has been working toward interoperability with other smaller carriers in the US as well, following a pledge in September 2013 to resolve compatibility issues between band 17 and band 12 in the 700MHz spectrum. (See AT&T Inks First LTE Roaming Deal in Canada and Mobile Migraine: Carrier Aggregation Roaming .)

It said last month that it will deploy a Multiple Frequency Band Indicator (MFBI) in its 700 MHz LTE network by the end of September, which will support LTE roaming for any carrier with a compatible band 12 device. It is also working with handset makers to offer devices that support band 12 MFBI via a software upgrade. (See Apple's New iPhones Have 20 LTE Bands, VoLTE and VoLTE: So Close You Can Hear It.)

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milan03 4/6/2015 | 7:09:21 PM
Re: the handoff trade off T-Mobile being another Tier 1 3GPP operator has had VoLTE with seamless handoff leveraging eSRVCC across the entire LTE footprint since last summer. T-Mobile however has LTE coverage challenges which had been the main cause of their higher drop call rate, and they've been addressing that by converting the entire 2G footprint to LTE at a furious pace. There isn't a valid excuse for AT&T taking their time with VoLTE rollout.

All new handsets come with VoLTE compatible hardware, so that's also not a good excuse for AT&T.

The real reason for AT&T not being quick on VoLTE front is unwillingness to invest into newer Release 10 infrastructure which would support features like VoLTE with eSRVCC, WiFi Calling, Carrier Aggregation, etc. They've been turning on these features opportunistically, sporadically, and completely random, so over the past year, in major markets like New York City they have a very small and isolated amount of sites that have been upgraded to support Carrier Aggregation, while the majority of the city hasn't been touched. 

This unwillingness to invest domestically is also evident in their latest advertising campaign claiming The Strongest LTE Signal, which literally brings no tangible benefits for end users.


danielcawrey 4/6/2015 | 4:24:45 PM
Re: the handoff trade off I think this is a smart way to go for AT&T. Let the competitiors drop calls. If AT&T wants to give the best experience to customers, then I guess that means limited handset availability.

I cannot see that as a major roadblock unless they did not have the iPhone. 
sarahthomas1011 4/6/2015 | 2:31:46 PM
the handoff trade off AT&T may not have nationwide VoLTE, but it does have seamless handoff, which is really important in avoiding dropped calls. That's why it's moving more slowly than Verizon and T-Mobile -- because it wants to make sure the experience is up to par with handoff. Limited handset selection also means not many of its customers are able to use it even where it is available. Anyone had experience with it yet? 
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