[Nexus 5X Q&A, Help & Troubleshooting] Lamuor:
Hi Guys,

For the past couple of days I have been trying hard to make VoLTE & VoWiFi work for an unsupported carrier(Airtel India). As known Nexus 5X supports VoLTE out of the box for only handful of networks and for the rest there should be some manual way to enable it. I am currently in India and have tested JIO network which worked out of the box in stock and LOS15 rom. And then recently moved to another location where I had to switch to Airtel and then no normals Calls/VoLTE except LTE data, very occasionally it does switch(not instantly) to GSM for calls.

I have started the work with a google search and XDA search where I have noticed many 3/4 years old devices including pixel, one plus, Xiaomi, Sony devices have come across similar issue and able to fix it manually. With the same spirit I tried some fixes that were intended for Pixel/other devices and failed miserably. Despite all the tries I still have high hopes and patience and looking forward to get some advice or even work together if anyone is interested. If anyone is wondering why I am so desperate on such a old device - honestly for me 5X is one of the best devices of the time and to date with some lineage OS roms(LOS 15.1, Havoc OS and /e/OS) and limited apps it runs very smoothly. Hardware was built well on budget except some manufacturing batches failed with boot-loop due to SoC assembly issues.

Note: I am an ordinary DIY'st with an interest in linux development and electronics and by no means an experienced developer. I am here to learn, unlearn and share experiences.

Below are the things I have tried so far ...

I tested the following methods on LOS 15/16/17 and the result is same. I have tried multiple times on LOS 15 because one of the senior member @razorloves said here that there are some serious bugs affecting the VoLTE functionality in LOS 16 and 17.

​

{Guide} QXDM Port activation on Pixel 2 XL, (VoLTE,WoWIFI,CA)​

First I followed the above guide with some changes, to enable diag port on 5X the commands are below taken from this reddit post

su
setprop sys.usb.config diag,adb

Next disable Sepolicy

setenforce 0

Installed latest Magisk zip for root.

Extracted modem config files from similar SoC/motherboard device rom. I checked the radio.img of bullhead 8.1 factory images which has MSM8994 model (see screenshots)

View attachment 5428275

Then I checked the wiki for Qualcomm devices which actually shows that MSM8992 is 5X but never mind I took reference from the factory images and started looking for modem files in MSM8994 devices. I searched quite a few devices and at last found files for Oneplus2, ZTE Nubia Z9 and Xperia Z5. All 3 devices had the carrier mbn files which I was looking for but then only Oneplus2 had exactly the same folder structure as the 5X factory image. I see Nexus 6P has similar SoC but I couldn't find a way to unpack the radio.img from factory build, if anyone knows a way then let me know.

As mentioned in the post installed Qualcomm drivers and QPST software, connected 5X. Device manager automatically installed additional drivers and 5X diag port is listed under ports. I opened the PDC tool under QPST, loaded all carrier mbn files from bullhead factory image, just to make sure they're loaded properly and be able to edit/delete. And the factory image mbn files all look good, then I removed all the files except default ones(which can't be deleted). Then tried loading the mbn files from all 3 devices but to my surprise none of them are loaded and there is no error/warning prompts. The PDC tool just keeps quite no matter whatever device file I load, except the factory ones. This is where I am stuck right now with no clue what's happening or what to be done to trace or fix the issue. I am thinking if everything fails then its possible edit mbn file to match the device/carrier???

Second day I continued my search and came across these two [GUIDE]Enable VoLTE for unsupported carriers & [GUIDE] Enable China Telecom LTE by modifying modem partitions

both are similar with different technique to insert files into 5X. I wasn't good at making Magisk modules so went with same old linux way as mentioned in the second link. And guess what none of them worked!!!

I even found the apns-full.xml and cross checked with the working carrier JIO and noticed that Airtel is missing IMS apn section. I copied the IMS apn section from JIO and modified the MNC, MCC and pasted below the Airtel sections, rebooted the phone with no luck.

I still believe that I might be missing something or there is a whole new way to do it, who knows? if anyone in this forum is interested to help or work together please let me know I will share all the files and logs if needed.

Mean while when I was searching the posts mentioned I have come across couple of members who have tried and worked hard to solve similar issue. I am tagging them below If they don't mind giving some inputs.

@Airpil

@somin.n

@Xdevillived666

Thank you guys I learned something from your struggles :)

PS: I was able to open/view EFS explorer all folder/file structure. I thought of being cautious and not to mess with EFS without knowledge, if that helps to find solution then let me know.