I can only grab the function names and some input parameters, and even then they're a bit muddy, e.g they don't declare if anything is returned.

I'll upload them to my branch on duoboot: https://github.com/Ethanol10/duoBoot/tree/extra-data/functionStrip

I've put my SIM back into A15 SD2, and for some reason it's picked up VoLTE and it works perfectly. Note this happened after I fully wiped from Stock 12L and set the following on v20241117 (The VoLTE patch one).

In phh treble settings -> IMS features:

• Install IMS APK for Qualcomm vendor -> install APK
• Request IMS network -> ON
• Force the presence of 4G calling setting -> ON
• Restart Phone after ims installation

In SIMs -> 1st SIM

• Select a compatible APN (You will need to look up your mobile phone provider for this) (should automatically be retrieved, just need to select the appropriate one)
• Carrier Video Calling -> ON
• WiFi Calling -> Doesn't seem to do anything, on or off.
• Preferred Network Type -> NR/LTE/TDSCDMA/CDMA/EvDo/GSM/WCDMA (just select all available types of communication)
• Roaming -> Off or On depending on if you need it
• 4G calling -> On

As for why it stopped working awhile ago, I have yet to test. Will do a device wipe and reinstall to see if that affects things before the VoLTE patch (e,g v20241108)

The following settings resulted in this when accessing the *#*#4636#*#* menu:

• IMS Registration: Registered
• Voice over LTE: Available
• Voice over WiFi: Unavailable
• Video Calling: Available
• UT Interface: Available

Seems to work fine on 20241108, wondering why this was an issue to begin with. Maybe the device had to be IMS registered in 12L before moving to A15?

Wondering if at any point the device will unregister itself and be back to the same issue I was at before

How is the battery drain thing?

I'm gonna be honest, I never noticed a severe battery drain during my usage before and after this issue