I am interested in moving away from a Pixel and getting the OnePlus. I am on Google Fi and I understand that moving to something other than a Pixel (or the handful of other "for Fi" phones) will leave me without network switching, and Google says no more WiFi calling or messaging. I am wondering if anyone has gotten the WiFi calling working on OnePlus on Fi, or the messaging. Thanks in advance.
defarstod said:
I am interested in moving away from a Pixel and getting the OnePlus. I am on Google Fi and I understand that moving to something other than a Pixel (or the handful of other "for Fi" phones) will leave me without network switching, and Google says no more WiFi calling or messaging. I am wondering if anyone has gotten the WiFi calling working on OnePlus on Fi, or the messaging. Thanks in advance.
Click to expand...
Click to collapse
With RCS being activated in the Messages app, the WiFi messaging should not be a problem. Not sure about WiFi calling though.
coolhandz said:
With RCS being activated in the Messages app, the WiFi messaging should not be a problem. Not sure about WiFi calling though.
Click to expand...
Click to collapse
I thought about that too with the switch to RCS messaging. I'd seen threads regarding wifi calling on OnePlus 7 on other sites but nothing about Google Fi, so was hoping someone here had experience. Thanks.
I have the Oneplus 7 Pro and Google Fi and it shows Volte and have no problems on it.
hedgehogmd said:
I have the Oneplus 7 Pro and Google Fi and it shows Volte and have no problems on it.
Click to expand...
Click to collapse
.
Basically I have this too. What I have noticed is that on some powerons and reboots, it's not there.... And then a later beboot, it comes back. So, not solid, AFAIAC.
defarstod said:
I thought about that too with the switch to RCS messaging. I'd seen threads regarding wifi calling on OnePlus 7 on other sites but nothing about Google Fi, so was hoping someone here had experience. Thanks.
Click to expand...
Click to collapse
WiFi calling works, and it hasn't on plenty of my devices.
Looks like Fi app has option for wifi calling now, have yet to test it out. No idea if device needs a reset Fi app uninstall to enable the toggle, if it's actually necessary. Installing Fi app always removed the option on activation and defaulted to the wrong apn on the first stable 10 build.
Cheers
blas4me said:
WiFi calling works, and it hasn't on plenty of my devices.
Click to expand...
Click to collapse
I was about to buy the OP7 Pro to replace my pixel 2xl,but then I read where wifi calling isn't supported. You're saying it definitely works?
Thanks
mmcneil said:
I was about to buy the OP7 Pro to replace my pixel 2xl,but then I read where wifi calling isn't supported. You're saying it definitely works?
Thanks
Click to expand...
Click to collapse
This is the first time I actually made a call with mobile data turned off. But, whenever I turn on wifi, I have a notification that it's enabled.
blas4me said:
This is the first time I actually made a call with mobile data turned off. But, whenever I turn on wifi, I have a notification that it's enabled.
Click to expand...
Click to collapse
Just to be clear, you're on Google Fi?
I'm using Fi and wifi calling is working for me.
Deltatko said:
I'm using Fi and wifi calling is working for me.
Click to expand...
Click to collapse
Thank you soooooo much! I appreciate the feedback.
mmcneil said:
Just to be clear, you're on Google Fi?
Click to expand...
Click to collapse
No, I have Optimum, I don't know anything about GF.
Custom rom? Are your enhanced network toggle and WiFi priority settings on the device? Fi seems to remove mine upon activation.
No such luck in airplane mode wifi.
Are you getting the VPN as well? None here.
I have to select the second apn after activation , drops mobile signal from tower to tower. Who knows if it's all correct I can't verify with tech support.
Thanks
Related
By going through the manual & comparing it to the EU version I've compiled a list of things tmous has changed on the phone. (in case anyone was interested)
Removed:
Quick Lookup - ability to select something & choose lookup through Google, Wikipedia, etc
Show Me app
Ebook reader completely missing even though HTC widget is still there
Voice Recorder
Voice Dialer
Dock settings
Locations
The Device Setup on first boot is missing things
Added:
Wifi calling (Tmobile's UMA feature)
I wonder why Tmobile removed all of these?
Here is a Voice Recorder app in the market that someone recommended since ours is missing:
http://market.android.com/details?id=com.tokasiki.android.voicerecorder
Did they keep Locations? And the quick look up thing is actually useful...dumb.
aNYthing24 said:
Did they keep Locations? And the quick look up thing is actually useful...dumb.
Click to expand...
Click to collapse
Ya, really dumb move by T-Mobile . Anyone know how to add quick lookup?
Sent from my HTC Sensation 4G using XDA Premium App
voice recorder is in there I'm sure,I'm sure I seen it
voice recorder is not in there...ive searched for it..theres a widget for it but when you click it it doesnt do anything..
aNYthing24 said:
Did they keep Locations? And the quick look up thing is actually useful...dumb.
Click to expand...
Click to collapse
seems to be missing too. updated post.
Man why the **** is it 3 years since using a HTC Touch and they are still locking in bull**** accuweather with no zipcode search or cities that aren't major?
Ran into the voicerecorder bs.
Is there anyway to add any of those features back in or are they hard built into the rom?
Added:
[LIST said:
[*]Wifi calling
[/LIST]
I wonder why Tmobile removed all of these?
Click to expand...
Click to collapse
What do you mean by "wifi calling"? is it calling via wifi using SIP provider?
If so, we do have it on our Vodafone UK branded units.
If it's something else, please explain.
well I guess it's good I havn't waited for the 4G to come and pre-ordered the British version.. just one thing, the WiFi Calling looks good.. (first time with Android and HTC xD) is there any way to get it in the UK Sensation Z710e ?
paulmor said:
What do you mean by "wifi calling"? is it calling via wifi using SIP provider?
If so, we do have it on our Vodafone UK branded units.
If it's something else, please explain.
Click to expand...
Click to collapse
T-Mobile is a pretty cool system. When you're at home (or on a WiFi network that doesn't do much filtering), phone calls, SMS, and MMS inbound or outbound route through WiFi instead of the cellular network. I've noticed this has the benefit of improving battery life while on WiFi, as it turns off the WCDMA (3G/4G) radio. It actually seems like it might turn off the cellular radio completely, I'll have to check when I get home.
The one downside is that if you are on the phone and walk away from your WiFi network, it will drop the call. It can't hand off.
I'm not sure if this is common in Europe, but in the states, many wireless carriers offer femtocell units that users can install in their home if they have bad reception. WiFi calling eliminates the need for that.
Wifi calling will notify you of a mms but it will not download the message. At least that's my experience with the G2x.
Sent from my LG-P999 using XDA Premium App
TheBigSaxon said:
Wifi calling will notify you of a mms but it will not download the message. At least that's my experience with the G2x.
Sent from my LG-P999 using XDA Premium App
Click to expand...
Click to collapse
ah sorry was just going off what I've been told regarding MMS. I actually don't use SMS or MMS, I use google voice for "SMS" purposes and don't have any use for MMS (if someone wants to send me a photo they just email it).
I have an unbranded phone from HK but also have Show Me and Locations. (Maybe the other stuff too - didn't check).
_kansei_ said:
I've noticed this has the benefit of improving battery life while on WiFi, as it turns off the WCDMA (3G/4G) radio. It actually seems like it might turn off the cellular radio completely, I'll have to check when I get home.
Click to expand...
Click to collapse
I think it shuts off the radio as well. My buddy had it turned on by accident & was freaking out because he was on wifi & showed no signal bars.
_kansei_ said:
T-Mobile is a pretty cool system. When you're at home (or on a WiFi network that doesn't do much filtering), phone calls, SMS, and MMS inbound or outbound route through WiFi instead of the cellular network. I've noticed this has the benefit of improving battery life while on WiFi, as it turns off the WCDMA (3G/4G) radio. It actually seems like it might turn off the cellular radio completely, I'll have to check when I get home.
The one downside is that if you are on the phone and walk away from your WiFi network, it will drop the call. It can't hand off.
I'm not sure if this is common in Europe, but in the states, many wireless carriers offer femtocell units that users can install in their home if they have bad reception. WiFi calling eliminates the need for that.
Click to expand...
Click to collapse
A similar feature to the TMOUS "wifi calling" is offered in the UK by BT Mobile. They call it BT Fusion.
Fem2cell is available here from Vodafone, known as Sure Signal
Subscribed in case someone posts the APKs to port over these missing features
quailallstar said:
Subscribed in case someone posts the APKs to port over these missing features
Click to expand...
Click to collapse
Good call, I'm gonna need wifi calling at the very least before I'll hop over to an alternate ROM (who am I kidding I'm sure I won't be able to resist). The my account app is handy but it's in the market anyway (there was an update a day or two ago).
When you say Dock Settings is there a separate App/Icon for the EU version or are the settings completely gone from withing the Settings Menu?
setzer715 said:
When you say Dock Settings is there a separate App/Icon for the EU version or are the settings completely gone from withing the Settings Menu?
Click to expand...
Click to collapse
It's in the settings menu & is gone from the US version
Guys, try installing these apk's for loacations . Not sure about last 2, try firs 2 at first, and then add last two if needed. Not sure if it will work, but worth a try
Is it possible to get the voice over data working on this phone?
Yes. I have it set up. Sprint's calling plus options allow for VOLTE and VOWIFI. They are both pretty nice, with only a few small issues.
Karlinski said:
Yes. I have it set up. Sprint's calling plus options allow for VOLTE and VOWIFI. They are both pretty nice, with only a few small issues.
Click to expand...
Click to collapse
So how would I get this going and what are the issues? Thank you.
Karlinski said:
Yes. I have it set up. Sprint's calling plus options allow for VOLTE and VOWIFI. They are both pretty nice, with only a few small issues.
Click to expand...
Click to collapse
Oh, never mind. I see they turned the VOD back on for this phone! Sweet! What are the issues though?
The issues I saw were WiFi calling related, not VOLTE. I have my phone set to kill wifi when the phone is in sleep mode. This also happens on a wifi call, but requires that you press the power button to trigger the sleep mode. I havent done a whole lot of experimentation beyond that one instance, though. I have had no issues with VOLTE, however.
Hi Dev’s,
I update my MIA1 to android oreo. When I search for Wi-Fi calling feature in settings, I notice that it is displayed. However when I click on Wi-Fi calling setting, It doesn’t dispaly under the Advanced Wifi settings.
My carrier supports Wi-Fi calling feature and I have it enables on my number. When I place the sim card in a iPhone, Wi-Fi calling works flawlessly. However it is not working in Mi A1 android oreo build.
Please can anyone help me get the setting activated on my mobile. I tried resetting the phone to factory settings, but I still don’t have the setting enabled.
ravivmc said:
Hi Dev’s,
I update my MIA1 to android oreo. When I search for Wi-Fi calling feature in settings, I notice that it is displayed. However when I click on Wi-Fi calling setting, It doesn’t dispaly under the Advanced Wifi settings.
My carrier supports Wi-Fi calling feature and I have it enables on my number. When I place the sim card in a iPhone, Wi-Fi calling works flawlessly. However it is not working in Mi A1 android oreo build.
Please can anyone help me get the setting activated on my mobile. I tried resetting the phone to factory settings, but I still don’t have the setting enabled.
Click to expand...
Click to collapse
Search using search button in settings app
Yash98 said:
Search using search button in settings app
Click to expand...
Click to collapse
Hi Yash,
Thanks for the reply.
I did search in the settings as suggested by you. I am able to see the Wi-Fi calling feature displayed in the search. However when I try to open the setting, it doesn't display. Please could post a screenshot of the setting from your Mi A1 mobile.
ravivmc said:
Hi Yash,
Thanks for the reply.
I did search in the settings as suggested by you. I am able to see the Wi-Fi calling feature displayed in the search. However when I try to open the setting, it doesn't display. Please could post a screenshot of the setting from your Mi A1 mobile.
Click to expand...
Click to collapse
Did you figure it out?? I experience the same problem: WiFi calling appears appears in search but tapping on it opens WiFi settings menu with no WiFi calling option it it.
Hi,
I still couldn’t get to see the optionto enable or disable wi-fi calling in settings.
Howeve one of the oreo testers replied in an another thread that wi-fi calling option is available in oreo beta build. He also posted a screenshot that shows option to toggle on/off the setting. Please let me know if you figure out a way.
Screenshots. I don't think my TSP supports it. Its !dea.
Just clear the Settings app's data.
ur0 said:
Just clear the Settings app's data.
Click to expand...
Click to collapse
I did clear the settings app data...now what?
---------- Post added at 09:10 PM ---------- Previous post was at 09:08 PM ----------
alkesh95 said:
Screenshots. I don't think my TSP supports it. Its !dea.
Click to expand...
Click to collapse
Same here.. my provider supports WiFi calling, it works fine with same sim card on my old LG G4. This is really frustrating
Open phone app
3 dot menu settings>
Calling account>
N/w provider mine is Jio>
WiFi calling
Ppfawade said:
Open phone app
3 dot menu settings>
Calling account>
N/w provider mine is Jio>
WiFi calling
Click to expand...
Click to collapse
Does it actually work? I mean on your Jio connection. I tried with iPhone and it doesn't seem to work. Yet.
buggerman said:
Does it actually work? I mean on your Jio connection. I tried with iPhone and it doesn't seem to work. Yet.
Click to expand...
Click to collapse
I think it won't work with hotspot from iphone or any other phone.
Correct me if i am wrong.
alkesh95 said:
I think it won't work with hotspot from iphone or any other phone.
Correct me if i am wrong.
Click to expand...
Click to collapse
I can confirm that Wifi calling on Jio is not active yet on any network (JioFi's wifi calling is something else so please don't bring that up) as on date. I have tried this on a Mi A1 also which supports Wifi calling out-of-the-box.
buggerman said:
I can confirm that Wifi calling on Jio is not active yet on any network (JioFi's wifi calling is something else so please don't bring that up) as on date. I have tried this on a Mi A1 also which supports Wifi calling out-of-the-box.
Click to expand...
Click to collapse
WiFi calling isn't available at any TSP. ( In india)
I once tried to call someone when connected to WiFi. There was a pop up to enable wifi calling. I enabled it from there. Since then it didn't appear again. Also I can't test whether it's working because my carrier doesn't support wifi calling
is there anyone with HTC u12+ on tmobile Us Verizone and Att with working wifi calling and volte who could share their default.xml file from system/customize/Acc and map_mns.xml system/customize and also all xml files from system/customize/mns trying to make wifi calling and volte on any htc u12+ or htc u11+
link to my thread
https://forum.xda-developers.com/u12-plus/how-to/wi-fi-calling-volte-t3867267
thanks for any help
The HTC u12+ for Verizon only has LTE capabilities. So all calls are by default VoLTE. However, WiFi Calling is a no go. It would be awesome if we could get that to work.
The files you need, do they contain any sensitive information about the phone? If not, I could grab you all the ones from my Verizon HTC u12+
JWhetstone02 said:
The HTC u12+ for Verizon only has LTE capabilities. So all calls are by default VoLTE. However, WiFi Calling is a no go. It would be awesome if we could get that to work.
The files you need, do they contain any sensitive information about the phone? If not, I could grab you all the ones from my Verizon HTC u12+
Click to expand...
Click to collapse
No there no imei or any other sensitive information in them only carrier settings etc
marcinkoko009 said:
No there no imei or any other sensitive information in them only carrier settings etc
Click to expand...
Click to collapse
here you go
Verizon HTC u12+
JWhetstone02 said:
here you go
Verizon HTC u12+
Click to expand...
Click to collapse
Thanks mate will check that later today and see the different against mine
JWhetstone02 said:
here you go
Verizon HTC u12+
Click to expand...
Click to collapse
hi mate i did check yours files and edited them according default.xml from verizon branded htc 10
can you do backup of your default.xml from system/customize/acc
then delete and copy attached one in
to copy that you need place on sdcard then boot twrp and use file manager built in adavanced settings and paste in system/customize/acc
then reboot your phone and let me know if you got wifi calling and volte working
you should be able see options under call settings and volte icon and wifi calling icon in statusbar
let me know if works
regards
I have WiFi calling options, but it killed data and service
JWhetstone02 said:
I have WiFi calling options, but it killed data and service
Click to expand...
Click to collapse
OK is Wi-Fi calling working at all ?
Will check that files again looks like I missed something
Just put your default.xml back
marcinkoko009 said:
OK is Wi-Fi calling working at all ?
Will check that files again looks like I missed something
Just put your default.xml back
Click to expand...
Click to collapse
WiFi calling did not work. All options were there, it let me uncheck and check, but when I went to make a call it wanted me to turn off airplane mode and wait for a mobile network to be available. and form the screenshot above, there is no mobile data.
Is there a way you can just edit the wifi calling stuff and not mess with the VoLTE. VoLTE is by default already on the phone through verizon
this is also what it shows as default from Verizon
just need to be able to enable the video and wifi calling
JWhetstone02 said:
WiFi calling did not work. All options were there, it let me uncheck and check, but when I went to make a call it wanted me to turn off airplane mode and wait for a mobile network to be available. and form the screenshot above, there is no mobile data.
Is there a way you can just edit the wifi calling stuff and not mess with the VoLTE. VoLTE is by default already on the phone through verizon
Click to expand...
Click to collapse
Yes I will try to check that again
Thanks for testing
JWhetstone02 said:
The HTC u12+ for Verizon only has LTE capabilities. So all calls are by default VoLTE. However, WiFi Calling is a no go. It would be awesome if we could get that to work.
The files you need, do they contain any sensitive information about the phone? If not, I could grab you all the ones from my Verizon HTC u12+
Click to expand...
Click to collapse
can u check that just do backup of your files and copy that in to system/customize
marcinkoko009 said:
can u check that just do backup of your files and copy that in to system/customize
Click to expand...
Click to collapse
Tried those files and this is what I have.
The video calling and WiFi calling are turned on under phone information
When going to phone > call > settings I cannot enable the WiFi calling in there. If I click it like 5 times, then it is enabled but it will turn off the time I back out the menu. Also it will not let me choose the preferred calling over WiFi vs Mobile network when it is enabled
JWhetstone02 said:
Tried those files and this is what I have.
The video calling and WiFi calling are turned on under phone information
When going to phone > call > settings I cannot enable the WiFi calling in there. If I click it like 5 times, then it is enabled but it will turn off the time I back out the menu. Also it will not let me choose the preferred calling over WiFi vs Mobile network when it is enabled
Click to expand...
Click to collapse
ok thanks i think we getting closer
4g still works and network signal as i can see so that is good
what is you phone cid?
JWhetstone02 said:
Tried those files and this is what I have.
The video calling and WiFi calling are turned on under phone information
When going to phone > call > settings I cannot enable the WiFi calling in there. If I click it like 5 times, then it is enabled but it will turn off the time I back out the menu. Also it will not let me choose the preferred calling over WiFi vs Mobile network when it is enabled
Click to expand...
Click to collapse
ok can u try attached last time for today
if not i will try dig around other forums to see if or what is missing
thanks for you help with testing
marcinkoko009 said:
ok can u try attached last time for today
if not i will try dig around other forums to see if or what is missing
thanks for you help with testing
Click to expand...
Click to collapse
I tried those files and it did indeed let me turn the WiFi Calling on and select which preferred way to go. But I could no longer make any calls. With it without WiFi enabled.
JWhetstone02 said:
I tried those files and it did indeed let me turn the WiFi Calling on and select which preferred way to go. But I could no longer make any calls. With it without WiFi enabled.
Click to expand...
Click to collapse
OK thanks I will dig some other forums to see if we can make that working
It's been a little while since your last update. Have you got wifi calling to work, and video calling???
thanks
k hammer said:
It's been a little while since your last update. Have you got wifi calling to work, and video calling???
thanks
Click to expand...
Click to collapse
Hi sorry but no luck
Greetings everyone!
Just got my Pixel 6a, love it so far, but i have one problem: Wifi Call doesnt work.
Whenever i try do a wifi call, i just get the message "out of network call"
Im using a german sim card from o2 (telefonica) and the thing is: my prior phone
was a redmi note 10 5g and with this phone (same sim card) wifi calling just worked like a charm.
so my question is: is there any trick to make it work? any explanation why it doesnt work with the 6a?
its a real bummer to go from a cheap a... redmi where this function just works fine to a nice and not so cheap pixel
(love google phones by the way, its my 3rd one), just to realize that something doesnt work as excpected.
i also tried a different os (calyx os), still no wifi-call.
help?
realCyphox said:
Greetings everyone!
Just got my Pixel 6a, love it so far, but i have one problem: Wifi Call doesnt work.
Whenever i try do a wifi call, i just get the message "out of network call"
Im using a german sim card from o2 (telefonica) and the thing is: my prior phone
was a redmi note 10 5g and with this phone (same sim card) wifi calling just worked like a charm.
so my question is: is there any trick to make it work? any explanation why it doesnt work with the 6a?
its a real bummer to go from a cheap a... redmi where this function just works fine to a nice and not so cheap pixel
(love google phones by the way, its my 3rd one), just to realize that something doesnt work as excpected.
i also tried a different os (calyx os), still no wifi-call.
help?
Click to expand...
Click to collapse
I'm using the Pixel 6a in Germany with o2 too - I've no issues with VoWifi and VoLTE. Are you shure you've enabled WLAN call in the accordant settings?
I use Google Voice...there an easier way w/o picking up an additional phone #?
On AT&T in the US...which is prolly why...lol
accuphase said:
I'm using the Pixel 6a in Germany with o2 too - I've no issues with VoWifi and VoLTE. Are you shure you've enabled WLAN call in the accordant settings?
Click to expand...
Click to collapse
i wrote that i used wifi calling with the redmi just fine, so i guess i know how to set it up, yes. so far i tried two o2 cards, no luck. question is, can you (you) really do phone calls by wifi or are you just using cellular without actually knowing. can you still do phone calls when airplane mode is on but wifi is enabled? do you see the wifi-icon onscreen (below number/name you're calling) when making a call?
realCyphox said:
i wrote that i used wifi calling with the redmi just fine, so i guess i know how to set it up, yes. so far i tried two o2 cards, no luck. question is, can you (you) really do phone calls by wifi or are you just using cellular without actually knowing. can you still do phone calls when airplane mode is on but wifi is enabled? do you see the wifi-icon onscreen (below number/name you're calling) when making a call?
Click to expand...
Click to collapse
can you really do phone calls by wifi ? Yes
can you still do phone calls when airplane mode is on but wifi is enabled? Yes
do you see the wifi-icon onscreen (below number/name you're calling) when making a call? Yes
realCyphox said:
i wrote that i used wifi calling with the redmi just fine, so i guess i know how to set it up, yes. so far i tried two o2 cards, no luck. question is, can you (you) really do phone calls by wifi or are you just using cellular without actually knowing. can you still do phone calls when airplane mode is on but wifi is enabled? do you see the wifi-icon onscreen (below number/name you're calling) when making a call?
Click to expand...
Click to collapse
Hi,
I'm having similar issues with my Pixel 6a, also in Germany. I use it with two SIM cards (o2/Telefonica physical SIM card and Vodafone eSIM). I have enabled Wifi Calling in the SIM card settings for both SIM Cards, but _most_ of the time, it doesn't work. The phone tries to use placing calls over cellular (my home office is in my basement, so cellular reception is pretty bad to non-existent, especially with Vodafone)
Most of the times, because sometimes it does work, then it shows up in the status bar and the wifi symbol is shown when placing a call. I couldn't yet figure out any correlation to when or why it works or doesn't, I have tried restarting the phone, putting it to airplane mode, deactivating and re-activating Wifi-calling - or just using one SIM card.
I'd say ~90% of the time it doesn't work.
btw I have used a Pixel 4a with the exact same setup / SIM cards before and didn't experience any issue whatsoever.
Do you have any workaround in the meantime?
Not sure if this helps any, but when entering *#*#4636#*#* on dialpad, going into 'Phone Information'
Is WIFI Calling Provisioned enabled like in my attachment?
Worth looking into:
How to Enable the Preferred WiFi Calling Option on the Verizon Pixel & Pixel XL
A tutorial on how to enable the Wifi Preferred mode in the WiFi Calling settings on the Verizon Google Pixel and Google Pixel XL.
www.xda-developers.com
andybones said:
Not sure if this helps any, but when entering *#*#4636#*#* on dialpad, going into 'Phone Information'
Is WIFI Calling Provisioned enabled like in my attachment?
Worth looking into:
How to Enable the Preferred WiFi Calling Option on the Verizon Pixel & Pixel XL
A tutorial on how to enable the Wifi Preferred mode in the WiFi Calling settings on the Verizon Google Pixel and Google Pixel XL.
www.xda-developers.com
Click to expand...
Click to collapse
Thanks for your answer. It is enabled for both sim cards indeed, though (WLAN-Anrufe eingerichtet is the option in German).
koenichlich said:
Thanks for your answer. It is enabled for both sim cards indeed, though (WLAN-Anrufe eingerichtet is the option in German).
Click to expand...
Click to collapse
Very welcome.
I'm sorry, I wish I was able to help with this!
I have found the error - it's actually caused by Blokada. I'm not sure whether it's just after some update of Blokada (I have used Blokada v5 for quite some time and regularly update) or the combination of Pixel 6a with Blokada, though. But Wifi calling always does work, when I disable Blokada.
Than I found this thread and have subsequently added com.android.phone and com.android.providers.telephony as bypass nad it does seem to work until now. Somebody else suggested bypass of Carrier provisioning service, I haven't tested yet, since as said it does seem to work now.
Just wanted to share my findings, if somebody else stumbles upon this thread.