[Xiaomi Poco F3 / Xiaomi Mi 11X / Redmi K40] Berik84:
If you have non-working VoLTE/VoWiFi on your current custom ROM here is how to solve it.

Requirements: Rooted phone

Qualcomm PDC Tool and Drivers (attached) (QPST)

PC + modem profiles (attached) + adb

I’m not responsible for any bricks/wipes/deaths/missing things etc. !!!

THIS GUIDE WAS TESTED ONLY ON POCO F3, TRY ON YOUR OWN RISK ON OTHER XIAOMI DEVICES

0. BACKUP YOUR EFS AND MODEM FILES AND REMEMBER WHAT WAS DEFAULT IN PDC

1. Find a correct profile for your carrier if you can and make sure your VoLTE/VoWiFi is enabled via dialer codes (*#*#86583#*#* for VoLTE and *#*#869434#*#* for WiFi, there should be a notification ‘VoLTE/VoWiFi carrier check disabled’ but not all ROMs have that)

2. Install QPST, install drivers (you may need to disable secure boot or some sh*t I dunno)

3. Connect your phone via USB with USB debugging enabled

4. Run adb and use these commands:

adb shell

su

setprop sys.usb.config diag,serial_cdev,rmnet,adb

(this last command may reboot your phone on some custom ROMs, in that case switch ROM or ask your dev to fix it or try it on the phone in Termux and then connect USB)

5. Open PDC (search via start)

6. Select your device in the dropdown menu (Qualcomm HS-USB WWAN Adapter 9091)

7. Select load and select a correct profile for your carrier (for example Profiles\EU\Vodafone\VoLTE\CZ\mcfg_sw.bin for Vodafone Czech)

8. Find your profile in the main window of PDC, right click on it a set for Sub 0 and 1

9. Select the profile you previously used for Sub 0 and 1 and select activate

It should look like this:

View attachment 5710541

10. Wait for it to hopefully load signal and work, try to reboot to see if the profile persists

11. Check VoLTE and VoWiFi on your phone, if it works congratulations, if not you may need to try other profiles and see if they persist after reboots

After reflashing ROM/firmware you may need to redo the whole procedure

These profiles were extracted from modem.img from POCO F3 firmware 13.0.7.0 SKHEUXM, not sure how it works with other global/indian/chinese versions, all profiles available are here:

mcfg_sw/generic/apac/aptg/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/airtel/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/cht/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/dcm/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/etisalat/commerci/uae/mcfg_sw.mbn
mcfg_sw/generic/apac/fet/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/kddi/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/reliance/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/sbm/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/twm/commerci/mcfg_sw.mbn
mcfg_sw/generic/apac/vdf_indi/commerci/mcfg_sw.mbn
mcfg_sw/generic/aunz/optus/commerci/au/mcfg_sw.mbn
mcfg_sw/generic/aunz/telstra/commerci/mcfg_sw.mbn
mcfg_sw/generic/aunz/vodafone/commerci/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/cmhk/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/commerci/volte_op/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/commerci/volte_su/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/agnss_lo/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/cta/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/conf_vol/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/eps_only/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/lpp_loct/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/nsiot_vo/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/rrlp_loc/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/tgl_comb/mcfg_sw.mbn
mcfg_sw/generic/china/cmcc/lab/w_irat_c/mcfg_sw.mbn
mcfg_sw/generic/china/ct/commerci/openmkt/mcfg_sw.mbn
mcfg_sw/generic/china/ct/commerci/subsidiz/mcfg_sw.mbn
mcfg_sw/generic/china/ct/commerci/volte_op/mcfg_sw.mbn
mcfg_sw/generic/china/ct/commerci/hvolte_o/mcfg_sw.mbn
mcfg_sw/generic/china/ct/lab/cta/mcfg_sw.mbn
mcfg_sw/generic/china/ct/lab/test/mcfg_sw.mbn
mcfg_sw/generic/china/ct/lab/test_eps/mcfg_sw.mbn
mcfg_sw/generic/china/ct/lab/test_no_/mcfg_sw.mbn
mcfg_sw/generic/china/ct/lab/volte_co/mcfg_sw.mbn
mcfg_sw/generic/china/cu/commerci/openmkt/mcfg_sw.mbn
mcfg_sw/generic/china/cu/commerci/subsidiz/mcfg_sw.mbn
mcfg_sw/generic/china/cu/commerci/volte/mcfg_sw.mbn
mcfg_sw/generic/china/cu/lab/test/mcfg_sw.mbn
mcfg_sw/generic/eu/a1/commerci/austria/mcfg_sw.mbn
mcfg_sw/generic/eu/bouygues/commerci/france/mcfg_sw.mbn
mcfg_sw/generic/eu/cellc/commerci/mcfg_sw.mbn
mcfg_sw/generic/eu/dna/commerci/finland/mcfg_sw.mbn
mcfg_sw/generic/eu/dt/commerci/cz/mcfg_sw.mbn
mcfg_sw/generic/eu/dt/commerci/pl/mcfg_sw.mbn
mcfg_sw/generic/eu/dt/non_volt/commerci/mcfg_sw.mbn
mcfg_sw/generic/eu/dt/volte/commerci/mcfg_sw.mbn
mcfg_sw/generic/eu/ee/commerci/mcfg_sw.mbn
mcfg_sw/generic/eu/elisa/commerci/fi/mcfg_sw.mbn
mcfg_sw/generic/eu/h3g/commerci/denmark/mcfg_sw.mbn
mcfg_sw/generic/eu/h3g/commerci/italy/mcfg_sw.mbn
mcfg_sw/generic/eu/h3g/commerci/se/mcfg_sw.mbn
mcfg_sw/generic/eu/h3g/commerci/uk/mcfg_sw.mbn
mcfg_sw/generic/eu/h3g/commerci/uk_rcl/mcfg_sw.mbn
mcfg_sw/generic/eu/iam/commerci/morocco/mcfg_sw.mbn
mcfg_sw/generic/eu/o2/commerci/cz/mcfg_sw.mbn
mcfg_sw/generic/eu/orange/commerci/france/mcfg_sw.mbn
mcfg_sw/generic/eu/orange/commerci/group_no/mcfg_sw.mbn
mcfg_sw/generic/eu/orange/commerci/poland/mcfg_sw.mbn
mcfg_sw/generic/eu/orange/commerci/romania/mcfg_sw.mbn
mcfg_sw/generic/eu/orange/commerci/spain/mcfg_sw.mbn
mcfg_sw/generic/eu/play/commerci/play/mcfg_sw.mbn
mcfg_sw/generic/eu/polkomte/commerci/mcfg_sw.mbn
mcfg_sw/generic/eu/proximus/commerci/be/mcfg_sw.mbn
mcfg_sw/generic/eu/sfr/commerci/fr/mcfg_sw.mbn
mcfg_sw/generic/eu/sunrise/commerci/switzerl/mcfg_sw.mbn
mcfg_sw/generic/eu/swisscom/commerci/swiss/mcfg_sw.mbn
mcfg_sw/generic/eu/tdc/commerci/denmark/mcfg_sw.mbn
mcfg_sw/generic/eu/tim/commerci/italy/mcfg_sw.mbn
mcfg_sw/generic/eu/tele2/commerci/nl/mcfg_sw.mbn
mcfg_sw/generic/eu/telefoni/commerci/de/mcfg_sw.mbn
mcfg_sw/generic/eu/telefoni/commerci/uk/mcfg_sw.mbn
mcfg_sw/generic/eu/telefoni/non_volt/spain/mcfg_sw.mbn
mcfg_sw/generic/eu/telenor/commerci/denmark/mcfg_sw.mbn
mcfg_sw/generic/eu/telenor/commerci/hungary/mcfg_sw.mbn
mcfg_sw/generic/eu/telenor/commerci/norway/mcfg_sw.mbn
mcfg_sw/generic/eu/telia/commerci/finland/mcfg_sw.mbn
mcfg_sw/generic/eu/telia/commerci/norway/mcfg_sw.mbn
mcfg_sw/generic/eu/telia/commerci/sweden/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/commerci/albania/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/commerci/greece/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/commerci/hungary/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/commerci/ireland/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/commerci/romania/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/non_volt/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/cz/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/germany/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/italy/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/netherla/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/portugal/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/rosario/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/safrica/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/spain/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/turkey/mcfg_sw.mbn
mcfg_sw/generic/eu/vodafone/volte/uk/mcfg_sw.mbn
mcfg_sw/generic/korea/kt/commerci/mcfg_sw.mbn
mcfg_sw/generic/korea/lgu/commerci/mcfg_sw.mbn
mcfg_sw/generic/korea/skt/commerci/mcfg_sw.mbn
mcfg_sw/generic/korea/tta/commerci/mcfg_sw.mbn
mcfg_sw/generic/latam/amx/commerci/mx/mcfg_sw.mbn
mcfg_sw/generic/latam/amx/non_volt/mcfg_sw.mbn
mcfg_sw/generic/latam/amx/volte/mcfg_sw.mbn
mcfg_sw/generic/latam/avantel/commerci/colombia/mcfg_sw.mbn
mcfg_sw/generic/latam/claro/commerci/colombia/mcfg_sw.mbn
mcfg_sw/generic/latam/telefoni/commerci/chile/mcfg_sw.mbn
mcfg_sw/generic/latam/telefoni/commerci/colombia/mcfg_sw.mbn
mcfg_sw/generic/latam/telefoni/commerci/ecuador/mcfg_sw.mbn
mcfg_sw/generic/latam/telefoni/commerci/mexico/mcfg_sw.mbn
mcfg_sw/generic/latam/telefoni/commerci/peru/mcfg_sw.mbn
mcfg_sw/generic/na/att/non_volt/mcfg_sw.mbn
mcfg_sw/generic/na/att/volte/mcfg_sw.mbn
mcfg_sw/generic/na/sprint/commerci/mcfg_sw.mbn
mcfg_sw/generic/na/sprint/vowifi/mcfg_sw.mbn
mcfg_sw/generic/na/tmo/commerci/mcfg_sw.mbn
mcfg_sw/generic/na/uscc/commerci/mcfg_sw.mbn
mcfg_sw/generic/na/verizon/cdmaless/mcfg_sw.mbn
mcfg_sw/generic/na/verizon/hvolte/mcfg_sw.mbn
mcfg_sw/generic/russia/beeline/gen_3gpp/mcfg_sw.mbn
mcfg_sw/generic/russia/mts/commerci/ru/mcfg_sw.mbn
mcfg_sw/generic/russia/megafon/commerci/ru/mcfg_sw.mbn
mcfg_sw/generic/sa/brazil/commerci/mcfg_sw.mbn
mcfg_sw/generic/sea/3hk/commerci/hk/mcfg_sw.mbn
mcfg_sw/generic/sea/ais/commerci/volte/mcfg_sw.mbn
mcfg_sw/generic/sea/apt/commerci/mcfg_sw.mbn
mcfg_sw/generic/sea/dtac/commerci/volte/mcfg_sw.mbn
mcfg_sw/generic/sea/digi/commerci/malaysia/mcfg_sw.mbn
mcfg_sw/generic/sea/fareasto/commerci/mcfg_sw.mbn
mcfg_sw/generic/sea/hkt/commerci/hk/mcfg_sw.mbn
mcfg_sw/generic/sea/m1/commerci/sg/mcfg_sw.mbn
mcfg_sw/generic/sea/p1/commerci/malaysia/mcfg_sw.mbn
mcfg_sw/generic/sea/singtel/commerci/singapor/mcfg_sw.mbn
mcfg_sw/generic/sea/smartone/commerci/hk/mcfg_sw.mbn
mcfg_sw/generic/sea/smartfre/commerci/vowifi/mcfg_sw.mbn
mcfg_sw/generic/sea/smartfre/commerci/mcfg_sw.mbn
mcfg_sw/generic/sea/starhub/commerci/singapor/mcfg_sw.mbn
mcfg_sw/generic/sea/tm/commerci/mcfg_sw.mbn
mcfg_sw/generic/sea/truemove/commerci/volte/mcfg_sw.mbn
mcfg_sw/generic/sea/umobile/commerci/malaysia/mcfg_sw.mbn
mcfg_sw/generic/sea/ytl/commerci/mcfg_sw.mbn
mcfg_sw/generic/ssa/ntel/commerci/mcfg_sw.mbn
mcfg_sw/generic/common/fih/nocard/mcfg_sw.mbn
mcfg_sw/generic/common/row/commerci/mcfg_sw.mbn
mcfg_sw/generic/common/row_cta/commerci/mcfg_sw.mbn
mcfg_sw/generic/common/row_gcf/commerci/mcfg_sw.mbn
mcfg_sw/generic/common/w_one/commerci/mcfg_sw.mbn

Tested by me, thanks to sjoerd for testing on his phone and thanks to skye dunno for trying on her phone