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iOS 8 supports voice over Wi-Fi, but what about voice over LTE?

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One of the nuggets to come out of Apple’s iOS 8 launch was the iPhone’s upcoming support for Wi-Fi calling. It’s a feature that not only will let consumers take advantage of carriers’ voice-over-Wi-Fi service, but is also the first step toward voice over LTE (VoLTE), which will put all mobile communications on IP networks.

The feature showed up as a mere bullet point in a long list of iOS 8’s new capabilities shown on screen at WWDC 2014, but T-Mobile(s tmus) immediately jumped, announcing it would bring its voice-over-Wi-Fi service to the iPhone when the new operating system becomes publicly available this fall. We’ll probably see a similar announcement shortly from Sprint(s s) and other global carriers offering Wi-Fi calling.

While there are plenty of apps that will let you make phone calls over the iPhone’s data connection, it’s been very difficult to make those services work with the iPhone’s main dialer. That’s why T-Mobile has been integrating Wi-Fi calling directly into its Android and Windows phones for years, but on iOS it has been forced to go over-the-top. For a while T-Mobile offered a separate VoIP calling app for iOS called Bobsled.

Image: Shutterstock / Sputanski
Image: Shutterstock / Sputanski

Over the years carrier Wi-Fi calling services have shrunk in importance since most voice plans have moved over to unlimited buckets, though for people living or working in a dodgy coverage zone or international travelers, those calling features are still a godsend. But VoLTE is a just a hop away and it could have a much more substantial impact on consumers and business users.

AT&T(s t) and T-Mobile(s tmus) rolled out their first VoLTE services last month, though right now they’re limited to a handful of Android phones and cities. Both carriers are offering HD voice, but VoLTE promises a lot more than just higher-quality phone calls. Verizon(s vz) has said it will launch VoLTE nationwide this year with integrated video calling, which could compete directly with Apple’s Facetime.

A host of other features like presence, instant messaging and integration with enterprise phone networks are other possibilities. While you get many of those services through third-party apps, VoLTE would integrate them directly into the dialer and attach them to your phone number.

I reached out to Apple about whether VoLTE support would be available on iOS but haven’t heard back yet. In its most basic form, VoLTE isn’t much different than Voice over Wi-Fi. It’s another IP connection, though carriers will be able prioritize voice and video calling traffic over their own 4G networks.


15 Responses to “iOS 8 supports voice over Wi-Fi, but what about voice over LTE?”

  1. komatineni

    Interesting point by Roanes. Also if this is going to change the way AT&T selling ‘small cells’ or Femto, am I right to say that market would be affected. As effectively the WiFi calling removes the need of coverage expansion by a diff device..

  2. BeachBum68

    I experience poor signal quality from my provider at home, so for my family, WiFi calling is a godsend. We only use wireless for phone service (no wired/land-line phones) and it’s not a matter of choosing a different carrier, they are all terrible for coverage when I’m at home. Plus AT&T and Verizon pricing is outrageous. T-Mo is very reasonable.

    I’ve been with T-Mobile for years now and yes, I’ve tried other carriers in the past (AT&T most recently, and Sprint. I won’t use Verizon mainly because of their bloatware and how they cripple handsets.) I only wish T-Mobile would make WiFi Calling packaged in an app so that you could bring an un-branded handset to them.

    Their choice of handsets however, is painful; I wanted to get an Xperia Z when it was time to upgrade. Can I get that in White? No. What about Google Nexus? I’d love to use them… Nope. It sucks because I have superb LTE service when I get into town. It’s so good, I could almost do away with home broadband… If I could only get that that good a signal at home.

    I’ve been looking at the LG G3 for my next phone upgrade, but I know if T-Mo offers it, it’ll be locked down and have bloatware I can’t get rid of without rooting. And forget about flashing a stock android build from LG or AOSP or CM. There goes WiFi calling out the window .

    This news will now force me to re-evaluate an iPhone 6 purchase.

  3. Claus Hetting

    I believe the new iOS Wi-Fi calling feature is a great step towards integrating Wi-Fi calling services into the mainstream mobile carrier ecosystem. I’m also not a big believer of VoLTE – which has been around for a long time, I think VoLTE a tough business case given that 3G networks work extremely well for voice (and now Wi-Fi too).
    There are also some implications here regarding indoor coverage. Indoor mobile coverage is often poor and it’s expensive to deploy indoor mobile networks – while Wi-Fi is everywhere indoors. The new feature will give carriers a real commercial shot at offering good indoor voice calls with Wi-Fi.
    If you want to know more about how Wi-Fi and mobile will work together very soon, come to the Wi-Fi Offload Summit in Palo Alto this month :-)

    • Kevin Fitchard

      Thanks for commenting Claus,

      Yep, that was the whole reason T-Mobile launched [email protected] way back when. It sucked you had to get their special Linksys router at first, but it was a handy way to boost home coverage without investing in femtos. The service was a bit sketchy at times so I stopped using it at home, but I made extensive use of it overseas.

  4. 3glteinfo

    Do you really have any idea what is VoLTE and WiFI Calling or fooling around. First of all VoLTE and WiFI Calling are two completely different technology.

    If Apple is supporting WiFi calling that does not mean that it will support VoLTE as well.

    Voice Over LTE enables traditional voice and SMS over LTE’s all IP network through IMS gateway. To implement VoLTE Apple needs new hardware inside iPhone. I do not think Apple like to have something new in iPhone.

    • Kevin Fitchard

      Thanks for commenting 3gLTE info,

      Many newer smartphones just need a VoLTE client to support calling. Maybe older iPhone models don’t have the hardware support for VoLTE, but I can’t imagine this will be a difficult thing to integrate into newer generation iPhones. Just because a feature isn’t turned on in iOS doesn’t mean it’s incapable of supporting it. Apple has time and time again turned on features with iOS update that have been partially backward compatible to older iPhone models.

      As for competition, sure there are some risks that VoLTE would compete with Apple services, but Apple can only be so territorial. It may be able to ignore NFC, but a standard the entire global mobile industry is behind is different.

    • Dragos Vingarzan

      Well “3glteinfo”, I think actually you must actually really just fooling around.

      No, there is no need for new hardware inside any phone to support VoLTE. And VoLTE and VoWiFi are not probably that different. Of course you can make them different, but from a carrier perspective you would want something well standardized by 3GPP/ETSI/3GPP2/etc. So you would use today IMS, which is basically SIP/RTP at protocol level, or in other words the telephony core for LTE.

      The difference is only the fact that on LTE you can provide QoS for signaling and media, while on WiFi you can’t (but who’d worry for 64kbps on their home WiFi). All this difference is network side, not phone side at all. If the VoWiFi is using SIP/RTP, then you can just use it on LTE. If the network side is Evolved Packet Core aligned to 3GPP Rel.8 or later, then you can derive network side all parameters without any changes in signaling and allocate QoSed bearers. If not you get WiFi non-QoSed on LTE, just that. Actually people don’t recognize that as a carrier once you have VoLTE you practically have also non-QoSed VoWiFi, VoWiMAX, VoWhateverIP.

      The tricky part is actually SRVCC and politics. Without that you can’t do really seamless handovers of calls between 2G/3G CS calls and the all-IP counterparts for LTE/WiFi/etc. So if you are not ready to accept broken calls when moving out of your WiFi hotspot, then operators have to upgrade and mess around with 20 years old equipment and that really hurts…

      • Rehan Siddiqui

        Very well summarized Dragos. All of these are different flavors of VoIP. If any carrier is using their a standardized IMS core to provide voice services, they can support any flavor of VoIP as long as it is supported by the handset.

  5. frank

    now if they would allow third party sip apps to integrate with the dialer like they can on android. i would like to go to my contact list and than call through cellular, skype, hangouts or sip client.

  6. Onno ter Wisscha

    The way I understood it from apple’s keynote is that your iPhone will act as a VoIP gateway: when you set up a phone call from your laptop a VoIP connection with your iPhone is established and your iPhone sets up a regular phone call to the number you’re calling. By te way: iPhones do VoIP natively for a long time already. It’s called FaceTime Audio.

    • Kevin Fitchard

      Hi Onno,

      All true, but I’m talking about something different. Apple is now supporting carriers’ Wi-Fi calling services, not just its own and third-party VoIP apps. Basically T-Mobile gives you the option of making any phone call over the Wi-Fi network or the cellular network, but iOS hasn’t supported that directly until now.