IMS user agent string in Carrier settings overrides?

ascension6817

I'm glad to see GrapheneOS's recent addition of the built-in carrier setting override feature. However, the change of carrier config interface breaks PixelIMS (see this comment), which is needed for changing the ims.ims_user_agent_string setting for successful IMS registration with my mobile carrier. Is there a chance for GOS to to include a config for overriding the user agent in the carrier setting overrides ui?

lbschenkel

ascension6817

Just clarifying that it was not this change from GOS that broke Pixel IMS but the latest security patches from Google. Google has blocked the mechanism that Pixel IMS has used to do these overrides. This will end up landing in all Android devices.

This is my gut feeling only, but I believe that the addition of the new settings in GOS side is exactly so users can have a working replacement for Pixel IMS.

23Sha-ger

ascension6817
Disable Pixel IMS, set the needed carrier overrides and check the status in * # * # 4636 # * # *
The new GOS feature is much more robust than Pixel IMS hack, and it's very rare for carriers to disallow a Pixel device for IMS registration just based on that string. Usually they keep a list of supported devices based on TAC (first 6 digits of the IMEI that specify the exact device model)

ascension6817

lbschenkel I'm not exactly sure what causes the breakage but I think it might be related to something GOS specific.

I expect Google's security patch to cause an exception that looks like java.lang.SecurityException: overrideConfig cannot be invoked by shell (related code path), which is what most people reports seeing on the issue.

Whereas on GOS the error looks like java.lang.NoSuchMethodError: No interface method overrideConfig (see full log).

I suppose this error is because of possible modification of the com.android.internal.telephony.ICarrierConfigLoader class. Please correct me if I'm wrong.

lbschenkel

ascension6817 Whereas on GOS the error looks like java.lang.NoSuchMethodError: No interface method overrideConfig (see full log).

I suppose this error is because of possible modification of the com.android.internal.telephony.ICarrierConfigLoader class. Please correct me if I'm wrong.

Oh, OK. That makes sense. I didn't realize it was a different exception. The only one I've seen was java.lang.SecurityException: overrideConfig cannot be invoked by shell and that was the one I thought you were talking about.

ascension6817

I tried uninstalling Pixel IMS and rely on GOS overrides alone. Although the VoLTE toggle shows up, IMS registration status is still showing unregistered from *#*#4636#*#*. Indeed my carrier seems to impose a restriction based on user-agent - see the discussion here https://github.com/kyujin-cho/pixel-volte-patch/discussions/268.

de0u

ascension6817 Indeed my carrier seems to impose a restriction based on user-agent [...]

Do all carriers in that country do that? I believe the GrapheneOS team added VoLTE forcing because a large number of users were in countries where Google's carrier configs for most or all of the major carriers did not enable VoLTE and meanwhile those countries are scheduled to turn off 2G and 3G calling entirely soon.

Code to override the IMS user-agent string seems potentially more niche, but if that's not the case then information about how many people are facing this problem might be useful.

ascension6817

de0u That's totally understandable! Fortunately, the newly released PixelIMS app still works on latest GOS, so I'm happy with the status quo as long as google don't break it again :)