IMS becomes unregistered on IMS Service Status menu when enabling VoWIFI

[drewnewvillage]

Describe the bug
IMS becomes unregistered on IMS Service Status menu when enabling VoWIFI on the settings app after following the instructions

To Reproduce
Steps to reproduce the behavior:

1. Go to Settings app
2. Tap on Network and Internet.
3. Tap on SIM
4. Turn on Wi-Fi calling
5. Go to Dialer and dial ##4636##
6. Tap on the Hamburger Menu
7. Tap on IMS Service Status
8. Menu will show "IMS Registration: Unregistered"

Expected behavior
I expected VoWiFi to work without making the IMS unregistered after following the steps. Network supports VoWiFi

Smartphone (please complete the following information):

• Device: Google Pixel 8a
• OS: Android 14
• Latest Security Update: July 2024
• Network: SMART Prepaid (Philippines)
• Pixel IMS App Version: 1.2.8

[BurhanBudak]

Pick the most stable state. Normaly the phone whitelisted thr IMS telephony. But IMS returns after some activity, thr phone losing IMS is for battery, especially during night.

[drewnewvillage]

IMS is registered if VoWi-Fi is enabled in Pixel IMS but turned off in the Settings app. When I turn it on in Settings, IMS unregisters.

[OliverRhyme]

Same here

[senposage]

pretty sure this a upstream pixel bug but adding this as it might help

https://docs.srsran.com/projects/project/en/latest/tutorials/source/cotsUE/source/index.html#ue-disconnects-after-a-few-minutes

For this purpose, open a hidden IMS settings menu by dialing ##0702## , then change one of the two following settings:

Infinite timeout: Set NR_TIMER_WAIT_IMS_REGISTRATION from default 180 to -1

Disable timeout: Set SUPPORT_IMS_NR_REGISTRATION_TIMER from default 1 to 0

under the hamburger menu > common settings you also might need to set

UPDATE_IMSCONFIG_BY_CARRIERCONFIG to 0 or prevent the carrier from overwriting your settings

there's a few other useful timeout variables in there that might help or harm