yashsingh1/xdaforums huggingface dataset:
[OnePlus 3 Guides, News, & Discussion] solk2:
It should work on any ROM where volte and vowifi works. At least on my LAOS it works. But it may require properties override (persist.dbg.volte_avail_ovr, persist.dbg.wfc_avail_ovr). But not sure about that as I have my own LAOS builds with carrier_config_26002.xml and I am too lazy to make new builds just to test it.

And this settings may be overridden by mcfg_sw update process which can happen while you updating ROM for example.
[OnePlus 3 Guides, News, & Discussion] ByKatre:
Can you create Vodafone TR? I can share ims settings.
[OnePlus 3 Guides, News, & Discussion] solk2:
I will share instructions how I made this one, probably today, and you can create it yourself.
[OnePlus 3 Guides, News, & Discussion] SpartaKurd:
It will be damn good!
[OnePlus 3 Guides, News, & Discussion] solk2:
Here: https://github.com/solk2/CNVParse
[OnePlus 3 Guides, News, & Discussion] meiser:
H,

this sounds very interesting. I'd like to try it for T-Mobile Germany, but I have some questions to understand it properly.

1. What ROM do you use exactly? You mention LAOS, but is it LAOS 13.0 or 14.1?

2. What exactly did you change in your self-built ROM?

3. I guess that I have to use the "Telekom.de DE" branded ROM to extract the system files (https://xpericheck.com/device/F8331). Is that right?

4. Currently, I'm running self-built LAOS 13.0 nightly which should have VoLTE integrated. Should the settings options for VoLTE already be shown? Or only after the modification?

5. Could you maybe point to a download location for QPST and the diag drivers? Or which version did you use?

Many thanks in advance,

meiser
[OnePlus 3 Guides, News, & Discussion] solk2:
1. and 2. I am using LAOS 14.1 with some my own modifications. But they aren't related to volte, vowifi or ril. Maybe only carrier_config_26002.XML in CarrierConfig but this can be achieved by system props. This method should work on any ROM. This is modem config so ROM should not matter.

3. Model is correct and I don't think that branding matters much. Looks like they are shipping all modem configs in all variants.

4. Settings will be show after you will add properties despite if modification was done right or not.

Or (but this is not tested) they will appear if modem config is correct and right apns added.

5. QPST is proprietary QC software so links to it here is forbidden. I was using 2.7.429.
[OnePlus 3 Guides, News, & Discussion] meiser:
Does this mean that I can already use your zip file as it also includes the modem config for T-Mobile Germany?
[OnePlus 3 Guides, News, & Discussion] solk2:
No. I've meant that you can find all configs in Sony ROM image for all regions despite which branding. But this config is made out of amss_fsg_kagura_telekom_poland_volte_vowifi.tar.mbn and you need something like amss_fsg_kagura_telekom_germany_volte_vowifi.tar.mbn
[OnePlus 3 Guides, News, & Discussion] meiser:
OK, so I downloaded the FW with XperiFirm, extracted it with FlashTool and mounted the system.ext4 to get the modem config "amss_fsg_kagura_telekom_germany_volte_vowifi_tar.mbn". I stripped the 552 bytes header and extraced the tar file.

But now I'm hanging at the next step. The nvpreload folder includes 3 files, but these are no tar files, just compressed data.

meiser@os:/tmp/modem$ ll nvpreload/
insgesamt 72
-rw-r--r-- 1 meiser meiser 353 Jan 1 1970 band_mapping_override.txt
-rw-r--r-- 1 meiser meiser 50650 Jan 1 1970 nv_L1234578_12_13_17_19_20_26_28_29_32_38_39_40_41.bin.gz
-rw-r--r-- 1 meiser meiser 115 Jan 1 1970 nv_L1234578_12_13_17_19_20_26_28_29_32_38_39_40_41_cal_true.bin.gz
-rw-r--r-- 1 meiser meiser 9163 Jan 1 1970 nv_L1234578_12_13_17_19_20_26_28_29_32_38_39_40_41_ets.bin.gz

Could you describe the next steps a bit more in detail? Right now, if I just uncompress the largest file, place the nvitems_list.csv in the root folder of the extracted modem config and run the jar file, I get the following error:

meiser@os:/tmp/modem$ java -jar cnvparse.jar
Exception in thread "main" java.lang.ArrayIndexOutOfBoundsException: 0
at ua.org.solk.qc.CNVParse.main(CNVParse.java:37)

At the end, VoLTE and VoWifi should work for both SIM slots as both have a T-Mobile SIM card (private and business). Does this work like this?

Thanks for your help,

meiser
[OnePlus 3 Guides, News, & Discussion] solk2:
Oops. My mistake. Not tar. You just need to run gzip -d nv_L1234578_12_13_17_19_20_26_28_29_32_38_39_40_41.bin.gz to uncompress it. And then you need to run java -jar cnvparse.jar /tmp/modem/nvpreload/nv_L1234578_12_13_17_19_20_26_28_29_32_38_39_40_41.bin .

nvitems_list.csv should be in same folder where cnvparse.jar and to that folder everything will be unpacked.

You will need to apply this config for both subscriptions to get both SIM cards working. So you will need to copy file to EFS twice. For first SIM copy them like it is. For second SIM you need to rename all files by appending _Subscription01.
[OnePlus 3 Guides, News, & Discussion] meiser:
OK, we're getting closer. :) What am I supposed to do with the out.xml file?

So I deleted all folders which are also not in your zip file. The folder structure is now as follows:

drwxr-xr-x 2 meiser meiser 4096 Jan 1 1970 data
drwxr-xr-x 2 meiser meiser 4096 Jan 1 1970 Data_Profiles
drwxr-xr-x 3 meiser meiser 4096 Jan 1 1970 ds
drwxr-xr-x 2 meiser meiser 4096 Jan 1 1970 efsprofiles
drwxr-xr-x 3 meiser meiser 4096 Jan 1 1970 nv
-rw-rw-r-- 1 meiser meiser 1211544 Apr 27 21:53 out.xml
drwxr-xr-x 2 meiser meiser 4096 Jan 1 1970 policyman
drwxr-xr-x 2 meiser meiser 4096 Jan 1 1970 sd

Do I have to rename really all files to name_Subscription01 or only the files in the nv folder?
[OnePlus 3 Guides, News, & Discussion] solk2:
Yes, looks good.

Probably not all. I think there no need to rename gps related files, they somewhere in nv folder. Maybe some other. But in any case it won't make worse. If they aren't used they will be just ignored. So just to be on a safe side rename all and copy them.

out.xml is NVItems file suitable for qxdm. It mostly contains bands settings and things like that. And we don't need to change that, so just ignore it.

EDIT: And delete nv/item_files/rfnv as that also bands related changes.

And you need to hexedit nv/item_files/ims/qp_ims_ut_config and add "internet.telekom" starting from second byte: So the beginning of file will look like this:

00000000: 0869 6e74 6572 6e65 742e 7465 6c65 6b6f .internet.teleko
00000010: 6d00 0000 0000 0000 0000 0000 0000 0000 m...............
[OnePlus 3 Guides, News, & Discussion] ByKatre:
Sony devices are not support Vodafone TR VoLTE? Can I take from Samsung Galaxy S7 firmware? Can anyone help me? :))
[OnePlus 3 Guides, News, & Discussion] solk2:
Nope. But if it's just VoLTE without VoWiFi you can try to copy /nv/item_files/ims files, /efsprofiles/imshandover and /Data_Profies/Profile8 from attached zip in first post. And then just add this APN:

<apn carrier="IMS"
mcc="286"
mnc="02"
apn="ims"
type="ims"
protocol="IPV4V6"
roaming_protocol="IPV4V6"
/>

It may work.
[OnePlus 3 Guides, News, & Discussion] meiser:
I just finished copying all the approx. 1700 files to the EFS from my created package.

I couldn't copy some files because of file length or file size.

After a reboot, I can't attach to the LTE network and I also don't see new VoLTE settings.

Any ideas?
[OnePlus 3 Guides, News, & Discussion] solk2:
Looks like you've missed this part:

RFNV files are related to bands. So restore EFS from backup and try again.

And yes, I forgot about some uim files. That ones are secured so you can't replace them and EFS manager just crashes. But they are not needed for VoLTE, that is related to sim card. So just skip them.

EDIT: And you need APNs for VoLTE to appear. Most important is apn="ims" type="ims".

EDIT2: And it looks like /nv/item_files/modem/data/3gpp/lteps/disable_apn_matching is missing in your config and it's quite important as it disables override of Data_Profiles by userspace APNs.
[OnePlus 3 Guides, News, & Discussion] ByKatre:
It hasn't worked bro. :(
[OnePlus 3 Guides, News, & Discussion] solk2:
Try to set property persist.dbg.volte_avail_ovr to true. It will force volte option to appear and volte may actually work.
[OnePlus 3 Guides, News, & Discussion] ByKatre:
Device is brick when I changed build.prop. :))

---------- Post added at 09:59 PM ---------- Previous post was at 09:37 PM ----------

I have edited build.prop. But this hasn't worked again. :( Is EFS partition reset when I wipe data or I flash ROM?
[OnePlus 3 Guides, News, & Discussion] solk2:
No, it's not like fully reset, but IMS configs most likely overridden by mcfg_sw update. So you need to copy files once more.
[OnePlus 3 Guides, News, & Discussion] meiser:
I updated my apns-conf.xml based on this commit: https://review.lineageos.org/162320

The file /nv/item_files/modem/data/3gpp/lteps/disable_apn_matching is already in the original EFS, so I hope it's okay.

But VoLTE settings still don't show up, and if I set persist.dbg.volte_avail_ovr to true, the mobile doesn't connect to LTE anymore.
[OnePlus 3 Guides, News, & Discussion] ByKatre:
I have changed just. Are they true?
[OnePlus 3 Guides, News, & Discussion] solk2:
You copied them as data files while they needs to be copied as item files.
[OnePlus 3 Guides, News, & Discussion] solk2:
Hm. This is quite weird. Did you reset APN settings after you modified apns-conf.xml?

And if it does not connect to LTE at all after property change then something happens at least. Do you have VoLTE enabled at carrier side? Coz I am not really sure what else can be checked.

Also check what exactly in this disable_apn_matching file. Its one byte file with 0 or 1 inside. It should be 1.
[OnePlus 3 Guides, News, & Discussion] ByKatre:
I copied file that you say me. Where do I mistake? :(
[OnePlus 3 Guides, News, & Discussion] meiser:
Yes, I reset the APN settings. VoLTE and Wifi calling is activated on carrier side, and disable_apn_matching is 1.

Maybe it's a ROM issue?
[OnePlus 3 Guides, News, & Discussion] solk2:
You can't use drag and drop. You need to do right click and choose copy item from PC.
[OnePlus 3 Guides, News, & Discussion] solk2:
Hmm. Hard to say. Can be. But its kinda weird to me that it cant connect to LTE at all. When I was experimenting I had like total drop of signal and RAT set to IWLAN. But I never had situation where it couldn't connect to LTE at all.

EDIT: Ah, it can be line with APN="" type="ia". Remove it. Better take APNs from here: https://android.googlesource.com/device/sample/+/master/etc/apns-full-conf.xml
[OnePlus 3 Guides, News, & Discussion] meiser:
The mobile connected to the LTE network after a reboot, even with the ia APN in place. But no VoLTE settings!

So there're 3 possibilities:

1. I did something wrong with all the modifications to the EFS.

2. The ROM is buggy.

3. The Oneplus3 FW doesn't support VoLTE. I have FW 3.2.8 on it. But I also tested the OpenBeta7 modem FW which is the last one for Android 6.0.1, no difference.

Please find attached my updated package.
[OnePlus 3 Guides, News, & Discussion] solk2:
And if you add persist.dbg.volte_avail property it can't connect to LTE, right? But does volte option appear in settings?

It can be modem FW. I remember there was bug reports on oneplus that volte didnt worked and its fixed in newer one. Maybe you need to upgrade to android 7.

EFS files looks good.
[OnePlus 3 Guides, News, & Discussion] ByKatre:
Still the same, mate. :(

---------- Post added at 10:03 AM ---------- Previous post was at 09:57 AM ----------

I am using OB14.

---------- Post added at 10:09 AM ---------- Previous post was at 10:03 AM ----------

And I haven't seen a connection problem. I am connecting LTE network but VoLTE is not wrking. :(
[OnePlus 3 Guides, News, & Discussion] solk2:
Does volte works with your sim card in Samsung phone?

As carrier can actually block VoLTE on non verified devices also. Also you can try to delete mcfgs in /system/etc/firmware/mbn_ota and in /data/misc/radio. Maybe OOS works differently and updates them on every boot.
[OnePlus 3 Guides, News, & Discussion] meiser:
I heard that T-Mobile Germany blocks non-verified devices. If this is the case, can the device model be faked somehow?
[OnePlus 3 Guides, News, & Discussion] solk2:
I am not sure how they are doing that. But I think that they can distinguish msm8996 devices only by IMEI. So you need to change beginning of imei to match Sony xperia xz for example, but I am pretty sure that its illegal in Germany.
[OnePlus 3 Guides, News, & Discussion] ByKatre:
I have tried the things that you told me, but still same. Back of the days, I tried to insert my SIM on iPhone 6. And VoLTE worked. So, VoLTE permissions allowed by my operator. Where is the problem? I don't know. :(((
[OnePlus 3 Guides, News, & Discussion] solk2:
I don't know. Check radio logs. VoLTE was first thing I've got working. As it only requires to be enabled in modem and proper APN. Also check if connections established by running ifconfig. VoLTE runs on rmnet_data6.
[OnePlus 3 Guides, News, & Discussion] meiser:
So I installed LAOS 14.1, and VoLTE works, but wifi calling not. With *#*#4636#*#*, it shows in the IMS status that VoWLAN is not available.

I had to add the following to /system/build.prop (don't know if I need them all, just added all at once):

[STRIKE]persist.dbg.ims_volte_enable=1[/STRIKE]
persist.dbg.volte_avail_ovr=1
[STRIKE]persist.dbg.vt_avail_ovr=1[/STRIKE]
persist.dbg.wfc_avail_ovr=1

EDIT: the striked ones are not needed.

And I enabled Wifi calling under "More -> Wifi calling" at set it to "network prefered" (or similar as it's shown in German :) ).

Anything I can do to get it to work?
[OnePlus 3 Guides, News, & Discussion] solk2:
Great. Try to add APN="hos" type="ia". I had to add it here in Poland to get it working.
[OnePlus 3 Guides, News, & Discussion] meiser:
Sadly no change.
[OnePlus 3 Guides, News, & Discussion] solk2:
Can you post which apns you have at this moment, including non visible ones.
[OnePlus 3 Guides, News, & Discussion] meiser:
Here they are:

<apn carrier="Telekom IMS" mcc="262" mnc="01" apn="ims" type="ims" protocol="IPV4V6" roaming_protocol="IPV4V6" />
<apn carrier="Telekom HOS" mcc="262" mnc="01" apn="hos" type="ia" protocol="IPV4V6" roaming_protocol="IPV4V6" />
<apn carrier="Telekom Internet" mcc="262" mnc="01" apn="internet.telekom" user="telekom" password="telekom" mmsc="http://mms.t-mobile.de/servlets/mms" mmsproxy="109.237.176.193" mmsport="8008" authtype="1" type="default,supl,mms" />

I guess, there're no hidden ones, but I'm not sure where to check exactly.

BTW, I switched back to LAOS 13.0 (self-built) as I got VoLTE working there (stupid typo with the build.prop settings :( ).

And I also got VoLTE working on SIM2!!!
[OnePlus 3 Guides, News, & Discussion] ByKatre:
How I do this? Can you private help me please? :)
[OnePlus 3 Guides, News, & Discussion] meiser:
I still try to get VoWifi working. I looked again at the Data_Profiles folder and found Profile2 and Profile2_Subscription01 which are not part of the Sony files. These profiles are somehow related to the APN "hos", but I'm not sure what I means exactly. Can the Data_Profiles files in any way be decrypted?

Please find attached the two Profile2 files.
[OnePlus 3 Guides, News, & Discussion] virusmoere:
Hi,

thanks for the Guide.

Can someone confirm VoLTE working on Vodafone DE with these patches? Is the modification to the EFS persistent to OxygenOS Updates and/or could the modification lead to problems during OxygenOS/Modem Updates?
[OnePlus 3 Guides, News, & Discussion] solk2:
Unfortunately I don't know any tool that can parse it. Neither I don't know structure of it.
[OnePlus 3 Guides, News, & Discussion] solk2:
This guide is for T-Mobile Poland. But you can try the way meiser going and try to make config for Vodafone DE.
[OnePlus 3 Guides, News, & Discussion] Darkje:
So guys in NL we have Tele2 that only listed a few phones to work with their VOlte. So with this truck it would be possible to get VOlte running on the OP3 in the NL? I have the option VOlte in my sim options. Although I cannot call with VOlte, it drops down to 3g.
[OnePlus 3 Guides, News, & Discussion] bighit101:
Any one trying this method on US TMO?

I tried doing it myself but had no success (I guess my technical skills are only good for rooting :) ).

Anyone?

Thanks
[OnePlus 3 Guides, News, & Discussion] solk2:
Why do you need this for TMO US. There is signed mcfg_sw by oneplus /etc/firmware/mbn_ota/mcfg_sw/mcfg_sw_TMO-Commercial.mbn. If its not picked up automatically then just load it and active it in QPST.
[OnePlus 3 Guides, News, & Discussion] emuandco:
Any way you could provide your recent files (if more recent ones are existent) and maybe a lil explaination what to put where and if it's Data or Item?

Some files in your op-modem-files archive seems to be missing (a few in between needed or not? and whole \nv\item_files\rfnv folder) compared to the archive in OP. And what makes me shiver is that some files seems to be there as data and are said to be added as item and vice versa...

And most important. Do stock LOS 14.1 bulds work with Telekom Germany carrier or do I have to do something here too?

Maybe [MENTION=3150073]meiser[/MENTION] or [MENTION=5291759]solk2[/MENTION] can tell me if the files meiser posted two sites behind are all I need or not? (Like.. anything to add to /etc/firmware/mbn_ota/mcfg_sw maybe) It's a bit difficult to understand if these files are what solk2 needed from the Sony phone to support LTE or some other file. Thanks for helping
[OnePlus 3 Guides, News, & Discussion] mrbeem:
Try to add this to build.prop for WiFi Calling:

persist.sys.cust.lte_config=true

persist.data.iwlan.enable=true

# Radio Options

persist.radio.rat_on=combine

persist.radio.data_ltd_sys_ind=1

persist.radio.data_con_rprt=1

persist.radio.calls.on.ims=1

# applying GPRI auto-commit

ro.radio_gpri=1

ro.amrwb_gpri=1

persist.data.iwlan=1

persist.data.iwlan.ipsec.ap=1

The last line with ipsec is added if you have an app called ipsec in your /system/app or /system/priv-app. Check it first, if you don't have the app, delete the last line

also check: /data/ipsec/wo/ what files you have there. Should have .conf files of all apns for VoWiFi VoLTE.

I activated VoWiFi on my LG G6 with stock based custom rom but i had to replace its original build.prop file with one from my carrier's VoWiFi enabled rom and to that build.prop i added all the extra bits from the custom ROM i'm on atm, plus the lines above. Last thing i did, i went to /OP and there i deleted a folder called _COMMON with all the content inside. Still in /OP i created a folder called SUPERSET. Then i went to OP/P4P_PL where i had config files for WiFi Calling and coppied all the content from the folder to /OP/SUPERSET. In SUPERSET i edited a file called cust.prop and changed the rootdir of cupps-capss prop /OP/P4P_PL to /OP/SUPERSET (second line in cust.prop)

In /OP i also had files called cust_group_mapping.cfg and official_op_resize.cfg. In 1st file i changed part after = to GLOBAL-COM (that is my base build i got from tapping IMEI SV in phone info). In second file i added at the top: SUPERSET_SIZE=(same size as my carrier's which was also on the list in the file).

- Deleting _COMMON forced my system to recognize my MNC-MCC code which is a crucial thing for apn registration.

- Creating SUPERSET and copying inside everything from my carrier's (P4P_PL) folder in /OP was to ensure that the system will always use my carrier's configuration, as if SUPERSET is present in /OP folder it is recognized by system as default one.

I also edited apns-conf.xml in /system/etc/ and added my needed apns there manually to be sure that my ims and xcap apns are always there, even if i restore all apns to default.

Last thing (that applies to LG phones) i had to do is turn on WiFi Calling toggles and settings in UI. I went into LG's hidden menu, Field Test->GPRI VoLTE/VoWiFi->UX and ticked UI settings i wanted to have visible.

P.S. make sure that in your build.prop you have a following line: ro.capp_cupss.rootdir=/OP as it shows the system where to look for your carrier's additional configuration files :)
[OnePlus 3 Guides, News, & Discussion] cosminnn:
Is there a way to edit the .mbn files with other network's values and then activate it? If you edit the file it will still be "signed"?

Or use a .mbn file from other device where volte works?
[OnePlus 3 Guides, News, & Discussion] cosminnn:
Any idea?
[OnePlus 3 Guides, News, & Discussion] article15:
Should i try that on OP5T?

thnx
[OnePlus 3 Guides, News, & Discussion] t-shock:
I was going to try and do that, but unfortunately, my carrier doesnt support any SD820 device for Volte
[OnePlus 3 Guides, News, & Discussion] suyashlimaye:
Great guide but can you please do that in English? Or do it for airtel/idea volte ?
[OnePlus 3 Guides, News, & Discussion] Menteslili:
Hallo Meiser kannst du mir Helfen ich finde diese Datei nicht, wie gesagt System.ext4 gemountet aber diese datei ist erhalten..""amss_fsg_kagura_telekom_germany_volte_vowifi_tar. mbn"
[OnePlus 3 Guides, News, & Discussion] devsx:
How can you load that?

I've tried this mod, but my phone is not even initiatinfg the IMS bearer.

The data profile folders are completely missing for my carrier.

Shouldn't it be possible to replace the stock mbn file on the OnePlus with for example the Sony one?
[OnePlus 3 Guides, News, & Discussion] jamal2367:
Thank you!

I have successfully enabled VoLTE and VoWiFi for o2 and Telekom Germany and Tele2 NL

The completly guide + files can find here:

https://android-hubo.de/thread/7983-anleitung-oneplus-3-3t-volte-vowifi-freischalten-de-nl/?pageNo=1

Screenshots in Attachments!
[OnePlus 3 Guides, News, & Discussion] NickosD:
Is there a way to activate it from COSMOTE in Greece? They support some devices, but not op3. They support phones you can buy from them and only after you flash their specific firmware.
[OnePlus 3 Guides, News, & Discussion] Darkje:
[MENTION=3068641]jamal2367[/MENTION] and [MENTION=5291759]solk2[/MENTION] Can you please assist me with setting this up for providers in the NL. i would like to get started.

Update:

Its working, big thanks to [MENTION=3068641]jamal2367[/MENTION]
[OnePlus 3 Guides, News, & Discussion] jamal2367:
Added Tele2 NL!

Link: https://android-hubo.de/thread/7983-anleitung-oneplus-3-3t-volte-vowifi-freischalten-de-nl/?pageNo=1

Further providers on request :)
[OnePlus 3 Guides, News, & Discussion] smatak:
Hi Jamal,

could you please make it on T-Mobile CZ (Czech Republic), please? :)
[OnePlus 3 Guides, News, & Discussion] jamal2367:
Come to the Forum and we can write private and i can help you :)
[OnePlus 3 Guides, News, & Discussion] emuandco:
Just tried your Telekom DE file but seems like LOS/AOSP based firmware is no good idea, huh? Still a call causes fallback to anything below LTE, settings for volte/vowifi are active though. One question regarding item file overwrite. When I throw (aka, right click item file import) the files in the correcponding folders they are found inside twice until a refresh, I think this is OK?

Here my *#*#4636#*#*

https://photos.app.goo.gl/zi9SFX2Qr43ET25M6
[OnePlus 3 Guides, News, & Discussion] puschkin:
Can someone make it also for Vodafone NL?
[OnePlus 3 Guides, News, & Discussion] Darkje:
[MENTION=1046656]puschkin[/MENTION] sorry i dont think we can. We cannot pull it from a device. [MENTION=5291759]solk2[/MENTION] and [MENTION=3068641]jamal2367[/MENTION] OR could we pull it from a Nokia perhaps..
[OnePlus 3 Guides, News, & Discussion] J_M_V_S:
It may be next to impossible, but if this can be adapted for Claro Argentina it would be highly appreciated. For Android they have both devices with built in support (sold by them) and through an app (https://play.google.com/store/apps/details?id=ar.com.claro.vowifiacs). For iOS it's built in. TIA
[OnePlus 3 Guides, News, & Discussion] Darkje:
If the Sony phone is There IT should be possible. You van follow the guide by extracting the mdn.
[OnePlus 3 Guides, News, & Discussion] Butit:
Eir network in Ireland supports WiFi calling, but only on limited phones purchased from Eir and with some postpaid sim plans. I don't know how possible it is to make it work on oneplus 3t and with a prepaid sim plan.