VoLTE in KR for Pixel 3/XL

Systemlessly activates VoLTE (Voice over LTE) on South Korean carriers

• SKT (SK Telecom)
• KT
• LGU (LG Uplus)

for blueline (Google Pixel 3) and crosshatch (Google Pixel 3 XL).

Prerequisite

If you're using PQ2A.190205.001 (February 2019 build) or later build, flash “radio-180917” first (or anytime) via fastboot mode.

adb reboot bootloader <Enter>
fastboot flash radio radio-crosshatch-g845-00023-180917-b-5014671.img <Enter>
fastboot reboot <Enter>

• You can get radio-crosshatch-g845-00023-180917-b-5014671.img (simply “radio-180917”) file from the factory image of PQ1A.190105.004 (January 2019 build). See Factory Images for Nexus and Pixel Devices webpage.

• For use on the SKT network, this is not mandatory. But doing this is recommended in case of replacing SKT SIM card with KT/LGU SIM card.

VoLTE Activation

Install Magisk if Magisk is not installed, since this is a Magisk module. Then,

1. Install this module on Magisk and reboot system.
2. After reboot, unlock the screen and wait 15 seconds.
3. Test VoLTE call and SMS. (optional)
4. Uninstall this module on Magisk and reboot system.
   • Even if you uninstall this module from Magisk, you can still use VoLTE on KR carriers.

After VoLTE activation, you may uninstall Magisk. Without Magisk you can still use VoLTE, again. Of course, you can continue to use Magisk without uninstalling it, for root features and so on.

OTA System Updates

1. For system updates via OTA, you need to restore the stock radio of current build.

   adb reboot bootloader <Enter>
   fastboot flash radio stock-radio-of-current-build.img <Enter>
   fastboot reboot <Enter>
   

   • You can get stock-radio-of-current-build.img file from the factory image with build number you're currently using. Know your build number and see Factory Images for Nexus and Pixel Devices page again.

2. Do OTA system updates completely, including reboot system.

3. After system updates, flash “radio-180917” (radio-crosshatch-g845-00023-180917-b-5014671.img) again via fastboot mode. (See above Prerequisite)

4. Test VoLTE call and SMS.

5. If VoLTE is not working correctly, re-activate VoLTE with Magisk and this module. (See above VoLTE Activation.)

Known Issues

Switching between SKT SIM and KT SIM repeatedly, VoLTE works on one carrier and CSFB(circuit-switched fallback) occurs on other carrier.

• SKT (First, VoLTE) > KT (VoLTE) > SKT (CSFB to 3G) > KT (VoLTE) > ⋯
• KT (First, VoLTE) > SKT (VoLTE) > KT (CSFB to 3G) > SKT (VoLTE) > ⋯

If you have an LGU SIM card, you can bypass this problem by sandwitching it.

• ⋯ > KT (VoLTE) > SKT (CSFB to 3G) > ⋯
• ⋯ > KT (VoLTE) > LGU (VoLTE) > SKT (VoLTE) > ⋯
• ⋯ > SKT (VoLTE) > KT (CSFB to 3G) > ⋯
• ⋯ > SKT (VoLTE) > LGU (VoLTE) > KT (VoLTE) > ⋯

Otherwise, re-activate VoLTE using Magisk and this module with proper SIM card inserted. (See above VoLTE Activation.)

VoLTE Deactivation

1. If you didn't uninstall this module yet, uninstall it and reboot system.
2. Remove fdr_check file in /data/vendor/modem_fdr directory (Root required.) and reboot system.

Note that uninstalling only this module does not deactivate VoLTE on KR carriers.

Update History

v1.04-20210314

• Fix for no newline at end of mbn_sw.txt
  • Thanks: 따이따잇

v1.03-20200214

• Support Pixel 3a/XL (experimental)
  • Thanks to gheron772 for revealing many things with regard to VoLTE activation for Pixel 3a/XL!

v1.02-20191218

• Reduce code duplication and clean up

v1.01-20190630

• Support device check on Android Q

v1.00-20190601

• First release
• Source(s) of carrier-specific modem configuration (mcfg_sw.mbn) files :
  • SKT, KT : Razer Phone 2 - Global Factory Image | P-MR1-RC003-RZR-190305.3110
  • LGU : Xiaomi Poco F1 - Global Stable ROM | V10.3.4.0.PEJMIXM

Acknowledgments

Thanks to : Occy and Chinese developers