[OnePlus 5T  Questions & Answers] lm8lm8:
okay guys, here is a little message to explain what happened

well, in a way I wanted, on OnePlus 5T, to enable volte or/and vowifi, for my ISP Free Mobile...

as several messages reported it (1), it was not an impossible operation. Mainly from xda howto, here is what happened.

1. with last andro running on 5T, I downloaded both apk to answer the original prcoess, with PDC software (whom is not maintained anymore)

while stuck on PDC detecting my device but blocking on an error message : dunno if the software is bugged or just new OT software doesnt allow it.

2. get back on the latest howto, running EFS command line howto (2). It was supposed to work. After several injection plus different reboots without volte working, a last one has been made but.. at reboot, the screen was totally black, with blue fixed led.

I factory reset it, wiping out everything (already saved before), then android was starting back but.. without any wifi/bt/cellular! It was stuck at the end of installation wizard : google doesnt allow usage of this phone, with last update, without connecting to google account, it forbidd it unfortunately.

3. I had so to find back a way to get back android+wifi/bt/cell : I spent hours and days looking for a solution to restore it ; I had no unlocked bootloader, and I finally discovered a way with Oneplus after sales tools (3), that made me able to get a new refreshed old android booting well, but still no wifi/cell/bt. Was however able, so, to unlock the bootloader.. with hope another android image from oneplus could work and bring back my cell working !

4. I was wrong.. so I opened a thread on XDA. Then I remind that on frenchy lafibre forum (dedicated to telecommunications), someone attempted to do so weeks ago... and was also stuck while, after (2) first operation, at reboot wifi/bt/cell were not working anymore too, with others feedbacks showing it! (4). Unfortunately, the link shown in the forums of onplus brings to "internal server error". After that, I did a little investigation to understand that the modem files has to be flashed again. Modem, wifi, BT. I did it several times, thinking fastboot was able to apply directly .img on the destinated partition of phone. Was wrong : erase the partition was necessary! (5)

fastboot erase modemst1

fastboot erase modemst2

fastboot erase modem

fastboot flash modem NON-HLOS.bin

fastboot erase oem_stanvbk

fastboot flash oem_stanvbk static_nvbk.bin

fastboot erase bluetooth

fastboot flash bluetooth BTFM.bin

Was then about to get back cell/wifi/BT ! but the tools of OnePlus doesnt do that.. EFS restoration is really something you have to backup before, and most brand doesnt restore it..

1:

Tutoriel - Activer la VoLTE et VoWifi sur OnePlus 6/7/8

Tutoriel - Activer la VoLTE et VoWifi sur OnePlus 6/7/8

lafibre.info

[Guide] VoLTE + VoWiFi working for German carriers

[UPDATE] Updated QPST version + new how to Exciting news, jamal2367 from https://jamal2367.com has developed a way to get VoLTE + VoWifi working for many countries + carriers. If you are on Vodafone and you are having problems with...

xdaforums.com

2:

https://xdaforums.com/t/guide-activate-volte-vowifi-oos-11-ob1-ob2.4223967/post-84365623

3:

https://xdaforums.com/t/op5t-latest-9-0-11-collection-of-unbrick-tools.3898890/

https://xdaforums.com/t/oneplus-5t-unbricking-tool.3733012/

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4: https://lafibre.info/4g/tutoriel-activer-la-volte-et-vowifi-sur-oneplus-7/msg782650/#msg782650

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5. https://droidwin.com/how-to-fix-corrupt-efs-no-imei-network-issues/