Beta VoLTE on the Xperia 10 III, disabled by default

The reason is: VoLTE is still in the beta stage and only the base set of functionality is implemented. Don’t expect other features to be already implemented, when a long awaited feature comes out as a beta version on a single device.

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It’s been over a year since I researcher the state of VoLTE, but to the best of my knowledge, you are correct. The problem seems to be that while how VoLTE works is well defined, how to actually implement it is not. Do carriers take the iPhone route and make users download an app (for those whose phones don’t have it built in), do you push software to the phone, do you utilize the SIM in some way, etc.? Everybody does it differently, if at all. IMHO this is where governments need to step in and tell their carriers that no changes will be made to their 2G, 3G, 4G, or 5G networks until they can prove interoperability with each other on a national level, and then with the outside world. Sadly AFAIK no country with a strong track record on consumer rights has gotten this ball rolling. I tried making some noise here in the US over a year ago, but no one seemed to be listening

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The first VoLTE phone was sold in 2012, and while I do expect interoperability testing was important during those early years, by now I would be surprised if all parties didn’t know how it works. The carriers know how major phone manufacturers implement VoLTE, and the phone manufacturers know how the carriers’ networks operate. The pessimist (honestly, the realist) in me says that some networks are precious because they make more $$$ that way. Either by selling customers new phones that have already been approved, or by charging the phone maker an exorbitant fee for compatibility testing. Here in the US, T-Mobile ran such a program for years. They still might. Back in 2018 when my XA2 was new, Sony apparent balked at the testing fee, and not wanting to upset T-Mobile, sold the phone with VoLTE disabled. But VoLTE was still sort of theoretical then, because the 2G and 3G networks were still robust. Now the chickens have come home to roost because with these networks waning to make way for 5G, you could be left with a phone that, due only to greed, may no longer be able to make calls. (Correct me if I’m wrong…towers can put out only so much signal, so that new 5G signal has to eat into something, a zero sum game.) And it makes me sick.

Caveat emptor: I am not a wireless engineer and have never worked for a wireless carrier or phone manufacturer. I can dig up links describing what is known of T-Mobile’s VoLTE compatibility testing program if anybody doubts me.


I’m interested in TMobile’s testing program, not because I doubt you but because I am curious.

This is what I have, from my research 1-2 years ago:

T-Mobile Unofficially Speaks To Us About Band 12 LTE / VoLTE And Unlocked Smartphones, And Yep It’s Still Confusing

Why Is T-Mobile Telling Manufacturers To Remove Band 12 LTE Support From Some Unlocked Smartphones?

T-Mobile and band 12 support in unlocked smartphones put in the spotlight

T-Mobile: All Band 12 LTE devices on our network must support VoLTE, E911

These are years old, but should still make good reading. In this context, the “band 12” issue is inconsequential, but note the article comments including those from the author. The person who collected the links speculates that T-Mobile’s certification program is no more.

Keep in mind that of the three national US carriers, T-Mobile is/was the most generous. At the time, AT&T operated a strict white list, the approved VoLTE phones consisting of no more than a few dozen phones, most of which they sold themselves. Verizon also used a white list, which wasn’t much better. Again, much of this could have changed. Sadly I don’t have time anymore to keep up the research and advocacy.


Maybe information in this post might help:

Thanks to @X0X0

Thank you. I was going to go looking for that sort of information. That should be very helpful.

A change is that my Blackview is no longer getting VoLTE on 2degrees. VoWiFi is still working though. Unfortunately neither works on the 10 III.
Tested Vodaphone today. Neither VoLTE or VoWiFi.
My mates Blackview does VoLTE on voda, but not VoWiFi.

If I could find anyone to ask, I would ask if they can provision them. It’s looking more like a whitelisting issue to me.

It would be useful to find out what which country the phone was intended to be sold in, Android software version was installed and what network operator the phone had been used on prior to flashing Sailfish.

Sony have this note on their specs regarding the installed bands. "Availability may vary depending on country, carrier, software version and user environment."

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Slightly OT, but out of curiosity, is there any change to get an official statement regarding upcoming or planned VoWiFi support, and X10ii support?
Thank you.

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I’m not aware that there’s been any announcement about VoWiFi support. You could ask about it at the community meeting, which is usually a good way to get specific answers to specific questions like this. However, since VoLTE is still beta functionality, I wouldn’t expect anything too concrete as an answer at this stage.

  • deleted, because obsolet -

I hope the XA2 will get the VoLTE support. Otherwise I’ll be forced to ditch Sailfish after all these years.


Wouldn’t it be easier to just ditch that ancient phone instead?


I ran the command, it did not register, did several reboots and have had it enabled for a day or so.

Using Telenor in Norway, it was working with Android

GetProperties returns:

method return time=1655818535.547857 sender=:1.11 -> destination=:1.535 serial=4508 reply_serial=2
   array [
      dict entry(
         string "Registered"
         variant             boolean false
      dict entry(
         string "Registration"
         variant             string "auto"
      dict entry(
         string "VoiceCapable"
         variant             boolean false
      dict entry(
         string "SmsCapable"
         variant             boolean false
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Thanks for reporting, if you don’t mind updating the Wiki with your findings so all info is in one place? VoLTE provider support

Do some people have collected experience with VoLTE mobility? Do thinks like call handover or fallback to 2G work reliable? Did people experience smooth calls when driving around with VoLTE enabled and so on?


I had some issues connecting to VoLTE. In the end I removed the SIM card and plugged it back in and after 4h of failing to register it worked immediately. I did try rebooting and other things before it. So if anyone has issues connecting, try removing the SIM tray for a few seconds.

I have the same message.
Using Tele2 provider in Lithuania.

First of all: My experience is somewhat ‘mixed’: It was not plain sailing to enable VoLTE support. As there is a setting in the mobile network section to enable ‘4G calling (beta)’, some questions came up:

  • why is it named ‘4G calling’ only, and no mention of VoLTE which is the one thing everybody looks for in that case? I’m okay with 4G calling in general, but why omit the official name of the standard behind it, especially when here and in official release notes it is always communicated as VoLTE-support? Such sudden naming changes or variations doesn’t make any sense and only lead to confusion in the general public.
  • I don’t remember if this setting in the mobile network section has been introduced in the previous version already, but it is not mentioned in this thread here, which still is the official resource to enable the beta VoLTe functionality. And here we see commands to be issued in the terminal requiring dev-mode to be turned on. So, I asked myself: What is the actual way to enable it now? settings menu or the command?
  • In fact I did both: first enabled the setting in the menu, then enabled dev-mode and issued the command. In addition it wasn’t told that you have to do this as root, which caused some more time to figure out, since only one user mentioned it here in the end of this thread (sigh).
  • Results: I can receive calls and it seems to be via VoLTE or ‘4G calling’, as the indication in the upper right stays on ‘4G’ → which is quite good at my place. However, 2G is not. And when I initiate a call, there is always a switch to 2G, still. However, this is not usable for me at the moment because of a loss of audio during calls when established using 2G. (see: Loss of audio during phone calls [Xperia 10 iii])

So in a nutshell: Yes, it works (partly) but the way to get to this status could have been better ‘paved’. The result is fine as long as its called ‘beta’ but still: Can anyone explain why it only works when I’m being called and not when I initiate the call?

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