Enabling Voice-Over-WiFi on the OnePlus 5T and Three UK

by @edent | # # # | 27 comments | Read ~7,852 times.

My mobile provider - Three UK - offers WiFi calling, but only if you have a phone purchased directly from them. For everyone else, they have a crappy app which hasn't been updated in two years.

So, let's break out of their artificial restrictions and get some WiFi calling on the OnePlus 5T!

Step-by-step

  1. Open your phone dialler app.
  2. Dial *#800#
    Dialler screen.
  3. You don't need to press send, you should automatically be taken to this engineering menu
    Log Test menu screen.
  4. Touch the top menu item "oneplus Logkit"
  5. Scroll to the bottom
    Log Menu screen.
  6. Press "Function Switch"
  7. Select "VoWifi switch"
    VoWifi Switch.
  8. Your phone will ask to reboot - so press OK to reboot
  9. Once the phone has restarted, go to your Settings menu
    Android settings menu.
  10. Select "SIM & network"
  11. Scroll down and select "Wi-Fi calling"
    Use WiFi Calling switch.
  12. You can optionally switch the "Calling preference" to "Wi-Fi preferred". If you do that, calls will go via Wifi even if you have a mobile signal.

Test it!

Put your phone into Aeroplane mode, then switch on WiFi. You should see this logo at the top of your screen.

VoWifi Logo on the top of the Android display.

Try to make a call.

It doesn't work??!

If this doesn't work for you... sorry! You should speak to your network provider to see what they recommend.

27 thoughts on “Enabling Voice-Over-WiFi on the OnePlus 5T and Three UK

  1. Ed says:

    This is outstanding, and exactly what I was after. Thank you for putting this on your blog :o)

    Cheers,

    Ed

  2. Simon Farnsworth says:

    If VoWiFi works, and the handset does VoLTE on networks that support it, you want to turn VoLTE on, too - assuming that the handset and network actually implement the standards properly, support for VoLTE will give you seamless call hand-off between WiFi and 4G (LTE) mobile networks, plus calling on 4G with seamless fallback to 3G/2G as appropriate (and fall-forward to 4G when in coverage), plus audibly glitchy handoff between WiFi and 3G/2G networks.

    On its own, this gives you better chances of sustaining a voice call; further, there's optional components to the spec that, if implemented at both ends, will give you seamless handoff between WiFi and 3G networks for voice calls, meaning that you can keep a voice call going until you lose coverage.

    For the nerds among us; VoWiFi and VoLTE are the same thing on different radio networks (both are SIP + RTP talking to the network operator's IMS service). In VoLTE, the IP packets are carried over LTE directly to your network; in VoWiFi, your phone establishes an IPSec tunnel to a well-known DNS name (epdg.epc.mncXXX.mccYYY.pub.3gppnetwork.org, where XXX is the three digit MNC, add a leading zero if you have a 2 digit MNC like 30, and YYY is the MCC, such as 234 for the UK).

    There's specified handovers to cleanly (no glitches) hand over the IP packets between radio types, and to switch from IP to circuit-switched voice if on the mobile network. There's also specified hand overs for IP to circuit-switched if not carrying IP over the mobile network (which are allowed to glitch), and an optional spec for carrying the IP packets over UMTS/HSPA instead of LTE.

  3. Essa Moshiri says:

    Hi, I just read your article and want to thank you for the kind and intuitive way you have kindly shared this information. However i have also found a potential bug / artefact.

    If like me you have 2 sims, and your primary sim is say Vodafone the Wifi Calling does not work. Wifi Calling only applies to the primary SIM it seems to me which is a shame.

  4. sam says:

    hi will this also work on the three UK network or could there be some other thing blocking vowifi thanks.

  5. Tasos says:

    Thanks! It works fine, Oneplus 5t and ID UK.

  6. Essa says:

    I just got it working on both Vodafone and three network. Managed to enable both WiFi calling and VoLTE.

    Confirmed WiFi calling but will need to confirm if VoLTE working.

  7. John Beardon says:

    You Sir, are a legend! Thanks so much for sharing this. I'm finally able to use WiFi calling on my Oneplus 5 using Three.

  8. Matt says:

    Just came across this on Google, was wondering that my phone must be new enough (oneplus 5t) to do vowifi on its own without the crap 'three in touch' app. Just tested sending an SMS and that seems to come through when sent on WiFi as well! Brilliant! Was always irritating having two separate places to look for texts. Thanks for sharing this, will make things much simpler from now on!

  9. Glenn A Harrison says:

    I have successfully enabled VoWiFi on my OnePlus 5T. However, even though VoLTE appears to be enabled and the boxes are ticked, it doesn't work. As soon as I turn off WiFi and initiate a call, it 4G cuts out and it drops back to 3G or H.

    I spent ages on the phone to Three but they cannot help.

    1. @edent says:

      Sadly, Three don't seem interested in supporting VoLTE on "unapproved" devices. You might try complaining to Ofcom to see if their behaviour is unreasonable.

      1. Simon Farnsworth says:

        If you have a friend with an "approved" device, it might be worth putting your SIM in their device, getting VoLTE enabled and working on that device, then swapping the SIM back to your device. If it's just a case of backend provisioning, this will trick Three's systems into turning on VoLTE on your account - and in my limited experience, once your SIM has been used for a VoLTE registration, the backend systems don't notice device swaps.

        1. Dave says:

          All Three handset sims are VoLTE provisioned, there is just some minor setting preventing VoLTE working on the 5T as using the above process you can activate VoLTE on the 3T for use on Three. I’ve even followed the more in-depth threads at XDA and frustratingly VoLTE won’t work on the 5T, no matter what (it does work on EE).

          Bizarrely though, on the 3T VoWiFi does not work, even though VoLTE does. Basically exactly the opposite of the 5T.

  10. J Oblong says:

    Verified as working, 2019-02-21.
    OnePlus 5 on Three UK.

    Thanks a million!

  11. Lou says:

    Does this work for Oneplus 3T on Three UK?
    Worked perfect on my 6T, but looks like wife might have to suffer the Three app a while longer!
    Tried enabling, but no joy.

    Thanks!

    1. @edent says:

      I don't have a 3T. Looks like she needs an upgrade 😁

    2. Dave says:

      The above process will get VoLTE (voice over LTE) working on the 3T, but on the newer software versions VoWiFi will not activate.

      VoLTE can be even more useful as it allows the handset to use Band 20 800MHz LTE on Three (what they call their SuperVoice service) which gives additional coverage for users.

      I’d swap having VoWiFi for VoLTE any day, I think it’s overall more useful, especially for use for in building penetration and coverage outside the main urban areas.

      1. Lou says:

        Cheers.
        Yeah, VoWiFi more use to us too as home is in a no-coverage area. Back to intouch app then.
        I'll add VoLTE anyway, no harm.

        1. Sam says:

          Just updated my OP3 to the Pie beta and interestingly the VoLTE and VoWiFi switches were enabled by default in the settings app. VoLTE worked immediately, VoWiFi isn’t working at all, as per comments above.

        2. Sam says:

          You must be as annoyed as me at the text from Three today about Three inTouch being end of life in two weeks?

          1. @edent says:

            I uninstalled the app when I activated VoWifi on my phone. Rubbish app.

            1. Sam says:

              Unfortunately, my Oneplus 3 won't work with VoWiFi for some reason following the above, leaving me with no options but to have a rant at Three customer services...

  12. Rob Ferrer says:

    Seems to work for O2, although you have to enable WiFi calling through the “MyO2” website.

  13. Benzpyrene says:

    Just activated this phone. I've downloaded a lot of apps over wifi already. I have done all of the above, but when I try to make a call in airplane mode I get "Prompt To place a call, first turn off Airplane mode. OK". When I turn off airplane mode I get "Mobile network is not available. Connect to a wireless network to make a call. OK"
    This is while I AM connected to a wireless network. What am I missing?

    1. @edent says:

      If you've switched on VoWiFi, you should see the icon shown in the post.

      If you don't see the icon, you WiFi network might be blocking calling.

  14. Roy Semple says:

    Is there a way to do this on a Sony XZ1?

  15. David says:

    Good job, thanks and you should run the Three tech support as they don't have a clue

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