Many have faced this problem while installing custom ROM on Redmi Note 3 you have to install Jio Voice app to call and default dialer doesn’t work. The following process will solve this issue with any Nougat ROM.
You will require following:
1. TWRP ZCX Recovery
Link- https://www.androidfilehost.com/?fid=385035244224409409 (This is must, other recovery may cause softbrick)
2. xiaomi.eu_multi_HMNote3Pro_6.11.3_v8-6.0.zip (Download from the below link only, it is not official or developer MIUI ROM) Link- https://www.androidfilehost.com/?fid=457095661767111758
4. Any Custom ROM I like Nitrogen OS
Link – http://xyyx-dev.ru/nitrogen-os/nougat/kenzo/
5. Gapps (Get the latest arm64, android 7.1, nano gapps.
Link – http://opengapps.org/
1. Start from any ROM, reboot into In TWRP ZCX , click ‘Wipe‘, then ‘Advanced‘, after that select ‘System’, ‘Dalvik cache’, ‘Cache’ and ‘Data’, and then ‘Swipe to wipe’.
2. Then go back thrice to return to the main menu and click ‘Install’ and find and select the xiaomi.eu_multi_HMNote3Pro_6.11.3_v8-6.0.zip package and ‘Swipe to confirm flash’.
3. Reboot into the ROM and select the default “internet” apn, do not add “Jionet” apn or any other (you have to enable volte in that default apn only).
4. Now volte may or may not work, reboot once and check again (in my case it did work the first time)
5. Then reboot into In TWRP ZCX , mount “cust” , go back and click ‘Install’ and find and select the CM14-firmware-20161115.zip firmware package and ‘Swipe to confirm flash’.
6. Reboot into the ROM, and now you must have VoLTE. Make a call and check. Then Reboot into the Recovery again.
7. (optional) Backup “EFS” and “MODEM” partition for future.
8. Now in TWRP , click ‘Install’ and select any VoLTE enable ROM currently I like Nitrogen OS rom and Gapps, ‘Swipe to confirm Install’. Reboot into the rom and volte will work.
For step by step guide you can also check out following video: