Update 2: How to get VoLTE and WiFi Calling on a Oneplus 6T on AT&T’s Network

This is option is meant for devs only. Enable at your own risk!

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These features are not meant for the average user. Only perform this at your own risk. Onetechstop is not responsible for any issues that may arise from enabling and using these settings.

What do you Need:

  • Oneplus 6T
  • Supported Sim Card (I’m using AT&T)
  • Patience
Oneplus 6T Information

How to Make it Happen:

  • Go into the dialer
  • Dial ” *#800# “
  • Press “Enter”
  • Then press “oneplus Logkit”
  • Lastly press ” Function Switch”
  • Check ” VoLTE”
  • Reboot
  • Repeat steps only instead of “VoLTE” press “VoWIFI” if you want WiFi calling as well.

After that complete these steps to check your work

  • Jump into settings
  • Press “Wifi & internet”
  • Then “Sim & network”
  • Then whatever sim is an AT&T Sim (mine was Sim 1)
  • Last you’ll see tabs for VoLTE and Wi-Fi Calling
Why should you do this?:

A main complaint of mine with Oneplus devices (and other unlocked phones) has always been that they don’t normally support VoLTE and Wi-Fi calling on AT&T. The devices normally have to be certified for that network to get these seemingly simple features.

Whenever I make phone calls my phone defaults to HSPA+ for a while and it takes time to switch to LTE. I also assume that voice calls sound more crisp and clear when over higher bandwidth networks. It will also make it so you don’t have to wait to get faster internet back each time you try to make a phone call. Lastly, if you’re in an area with low coverage you can still make calls over Wi-Fi.

Why should you NOT do this?:

This feature is meant only for devs. We don’t know how stable it is or how well it will work in the long term. I personally only just enabled it so I cannot speak for its stability. Only do this at your own risk! I was recently on a voice call using this setting and it sounded really good, however the call randomly hung up and there were no service interruptions. Voice calls were also much louder so the person on the other line may hear their own voice if you don’t turn down the volume.

Conclusion:

Please let me know if you or anyone else tries this as well as your experiences with the hidden features. If you have a device other than the 6T please let us know if it work on your device!

Update #1: 12/30/2018

I ran a few specific tests after testing the stability of the VoLTE and Wi-Fi calling since writing this article on December 21st, 2018. Stability has been fine for me. I have not noticed any dropped calls calling to other devices with VoLTE and Wi-Fi calling as well as those without it. I call people at least once a day, most times I make 5-6 calls a day. Without any dropped calls and updating to Oxygen OS 9.10 and still having no options I’d say this is mostly stable.

Tests:

Note: I could not disable cellular calling for any of these tests. I will need to find a place with no cellular connection

Mobile Data off with Wi-Fi on and VoLTE and Wi-Fi calling enabled:

I saw no issues in stability. Calls came through fine and I did not find any stuttering. This call was made to a land line. The pictures below show the call being made and the settings that were used.

Mobile Data on, Wi-Fi on, VoLTE on and Wi-Fi Calling on Preferred calling setting was VoLTE:

This call was made to an iPhone 7 plus on AT&T’s network. Whenever you see the “HD” symbol I am assuming that means that means VoLTE is being used and not Wi-Fi calling. Calls come in far more clear when VoLTE is being used and I don’t notice as much crackling. I’m assuming that’s what HD voice is supposed to do. Regardless I do notice a difference. If you aren’t used to HD voice you will definitely notice a large difference.

All Settings on
VoLTE off Wi-Fi Calling on,  Mobile Data off and Wi-Fi on:

The HD symbol is gone, however I don’t know if this call is using Wi-Fi or cellular. As I explained above there is no way for me to check where the call is coming out of. I will note that the call did not sound as crisp. The person I was calling was the same person with the same iPhone 7 Plus with no settings changed on their end. I changed the calling preference to prefer Wi-Fi calls in this test.

VoLTE and Wi-Fi calling off, Wi-Fi on and Mobile Data off:

The call still went through just fine to the iPhone 7 Plus. Calls are definitely not as crisp without the HD voice going through. Wi-Fi Calling is still the preferred calling method. I can assure you this is just regular calling. All additional settings are off. The next test will show you why changing the preferred calling method is very important for testing Wi-Fi calling.

Final Test: All Settings on (Mobile data, VoLTE, Wifi and Wi-Fi Calling) with Preferred calling setting set to Wi-Fi Calling:

This test is to prove that the preferred calling setting matters. You’ll notice that although VoLTE and mobile data are on there is no HD symbol next to the caller. This means that the call is either going through Wi-Fi or cellular. The call was still muffled as though it was going through cellular. The only way to most accurately test this setting is to find a place with no cellular, or LTE service. Only Wi-Fi. When I find a place like that I’ll update the article.

Update 2: Wi-Fi Calling with Airplane Mode

This update will be short and sweet. Unfortunately, Oneplus does not allow calls to go out, even over Wi-Fi when the device is in airplane mode. I will post the prompts I received below. I am going to continue looking for a space where I get absolutely no service and only Wi-Fi. Those places are not common by me but when I find them you will all be the firsts to know.

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