How to prevent XZ2 Compact from using VoLTE ?

[v0ujiemq]

Hi. I have a XZ2 Compact since a couple of weeks. My contract (Congstar, using german T-Mobile network) includes 4G for data, but only 2G/3G for calls. So the phone should change to 2G/3G mode if I call someone or someone call me. Sadly it only does, if there is 4G coverage at the beginning of the call. If there is only 2G/3G coverage at all I can't call anyone. So the phone always try to use VoLTE first before the network force it to use GSM for calls.
How can I force the phone to avoid VoLTE at all? I know there should be a option for this in the connections menu, but it's just not there. I tried a hard reset and I also flashed another firmware which I downloaded with XperiFirm. At the moment I have 52.0.A.8.50 installed.

 

[MartinX3]

Hi. I have a XZ2 Compact since a couple of weeks. My contract (Congstar, using german T-Mobile network) includes 4G for data, but only 2G/3G for calls. So the phone should change to 2G/3G mode if I call someone or someone call me. Sadly it only does, if there is 4G coverage at the beginning of the call. If there is only 2G/3G coverage at all I can't call anyone. So the phone always try to use VoLTE first before the network force it to use GSM for calls.

How can I force the phone to avoid VoLTE at all? I know there should be a option for this in the connections menu, but it's just not there. I tried a hard reset and I also flashed another firmware which I downloaded with XperiFirm. At the moment I have 52.0.A.8.50 installed.

Usually no button means no support

I would ask the Sony support about this problem.
It may be a software bug.

 

[v0ujiemq]

So there is no quick solution? I would like to use my phone without waiting for a bugfix And I'm pretty sure I'm not the only user of this phone in germany and this "LTE only for data" sim card are pretty common here.

 

[MartinX3]

So there is no quick solution? I would like to use my phone without waiting for a bugfix And I'm pretty sure I'm not the only user of this phone in germany and this "LTE only for data" sim card are pretty common here.

I am a German user too, but with O2.
It's working here without any problems.
Like VoWIFI

 

[v0ujiemq]

I am a German user too, but with O2.
It's working here without any problems.
Like VoWIFI

As you maybe know, O2 support VoLTE and Wifi Calling for all customers, also for reseller like blau, ay yildiz etc.
T-Mobile and Vodafone only allow VoLTE and Wifi Calling for their own customers, not for reseller like Congstar, Otelo etc.

 

[MartinX3]

As you maybe know, O2 support VoLTE and Wifi Calling for all customers, also for reseller like blau, ay yildiz etc.
T-Mobile and Vodafone only allow VoLTE and Wifi Calling for their own customers, not for reseller like Congstar, Otelo etc.

So I would ask the sony support, if it won't show a disable button.
Or use a SODP based custom rom. (Here VoLTE and VoWIFI is on the todo list).

Maybe one of the many listed adb props helps you, too.
http://bfy.tw/ONWv
But that would be just a forced disabling via ADB.
Not fixing the root cause of the issue.

 

[v0ujiemq]

Sony answered very fast, but just said I should contact my network provider. Well, useless as they only care about devices customers bought directly from them and not on the free market.