GrapheneOS
Removing SIM and erasing network settings doesn't stop Wi-Fi calling DNS resolution
When Pixel 4a phone is fully wiped (both boot slots), flashed, and GrapheneOS is installed without any SIM being present, the phone does not make any attempts to resolve ePDG (MNC, MCC) domains over WiFi (in Airplane mode) for WiFi calling because that information comes from SIM and WiFi calling must be authenticated via SIM. Without SIM, the phone doesn't know which domains to resolve and cannot perform WiFi calling. That's normal behavior.
Once SIM is inserted, phone starts trying to resolve ePDG domains over WiFi (in Airplane mode) even when WiFi calling is disabled. That's also normal behavior.
Once SIM card is removed, network settings are wiped/erased/reset, and phone is rebooted, it keeps trying to resolve the same ePDG domains over WiFi (in Airplane mode) for carrier of the removed SIM card. Why? Once SIM card is removed and network settings are wiped/erased/reset, phone should not know which WiFi calling domains to resolve. There shouldn't be any trace of previous SIM. That doesn't appear to be the case. It appears as if inserting SIM card into phone one time registers that phone to SIM card carrier, even if SIM card is later removed and network settings are wiped/erased/reset. The only way for phone to fully forget SIM card information is to perform full factory reset. That is either not normal behavior or shouldn't be...
Small update: If SIM card is inserted, but disabled via toggle in network Internet settings, the phone also tries to resolve ePDG WiFi calling domains. SIM card is needed to authorize WiFi calling and if SIM card is disabled, I think it is expected for phone to not try to resolve WiFi calling domains.
Closing assuming this is fixed due to inactivity and no one else has reported/confirmed this issue. May have been fixed with QPR2. If this is still an issue let us know.
I can reproduce this on Pixel 4A but not on 6A, so it's most likely something Qualcomm SOC-related configuration.
edit: It's only reproducible when DSDS is enabled.
@empratyush can you reproduce with DSDS enabled on both the 4a and the 6a to be clear?
@empratyush We might be able to workaround this if we clear the data of the Qualcomm IMS app if a SIM card gets removed or added.
@empratyush Would suggest trying this to see if that mitigates the issue.
@empratyush Would suggest trying this to see if that mitigates the issue.
No it doesn't fixes the issue, afaict IMS directly communicate with radio.
Hmm, that is unfortunate. Given that we will soon only have 1 Qualcomm Pixel left with security support by the end of the year, it might not be worth looking into.