Add 'Force SA' toggle in Carrier settings overrides > 5G Capabilities

NeilBrown228

Hello, I'm a longtime user of GrapheneOS and first I would like to thank the team behind the OS.

Before the Carrier settings overrides were implemented I was using the PixelIMS tweak in order to have some features such as Wi-Fi Calling. This new system is great and really straightforward to use.

The thing is I'm missing an option in the '5G Capabilities' tab. Currently the only available tweak is to force both NSA and SA modes. Would it be feasible to implement a new toggle to force the Standalone mode (SA) only?

Thank you in advance, I'm open to further questions should I need to clarify my petition.

wizoatk

NeilBrown228
Can you explain why setting "5G Only" for the "Preferred network type" in the SIM settings doesn't address your use case or why you want to skip 5G NSA as a fallback?

You may want to see if there's any overlap with existing issues:
https://github.com/search?q=repo%3AGrapheneOS%2Fos-issue-tracker+%225G+Only%22&type=issues

NeilBrown228

Thank you for the feedback. If I set the '5G Only' mode the phone is able to connect to 5G NSA but it won't connect to 5G SA, whenever is available. This is confusing to me given that I'm able to connect to 5G SA with the same carrier at the same spot using a different user equipment (which is not a Pixel phone).

I'm currently using a Pixel 9a with GrapheneOS and before Carrier settings overrides were implemented I would try to force a change in the "carrier_nr_availabilities_int_array" key from 1 to 2, using the PixelIMS tweak. The app just crashed so that wouldn't work either. Apparently the same tweak did work (therefore connecting to the 5G SA) for some stock Pixel users. I'm getting this info from a Spanish forum.

This is the most closely related issue that I could find https://github.com/GrapheneOS/platform_frameworks_base/pull/246. In fact my carrier (Movistar Spain) is the same as the user there who wanted to merge a pull request. That pull request was closed by a member of the GrapheneOS team noting that it was not the way to fix the problem, which was 5G SA not working.

As long as I'm forcing both NSA and SA modes in the '5G Capabilities' tab of the Carrier settings overrides, phone is able to connect to 5G in NSA mode but not in SA mode. However, a user of the Spanish forum I mentioned earlier says they were able to connect to 5G SA in GrapheneOS using the Carrier settings overrides.

After further browsing and given all the info I found I'm still a bit confused, as this could be a carrier-side issue. If you think so, feel free to close this ticket.
I'll try to contact my provider to see if they are able to fix the issue.

Thank you for your help!

wizoatk

NeilBrown228 If I set the '5G Only' mode the phone is able to connect to 5G NSA

I cannot reproduce this behavior. Specifically I have SIMs for two different carriers which connect with 5G NSA service. On both SIMs and whether or not the 5G Capabilites are forced or not, If I enable 5G only then the phone will try to connect to 5G service (which is available) but fails because 5G SA is not provisioned for the service. This can take up to a minute. Contrary to your report my phone does not fall back to 5G NSA. My understanding is that is the expected and correct result.

this could be a carrier-side issue

Odds are, yes. Whether there is something that GrapheneOS could do to work around it isn't at all clear.

NeilBrown228

Good news! I can confirm it happened to be a carrier-side issue. Yesterday I was able to connect with 5G SA service. This was after talking to my carrier's tech support. Thanks again for your help and advices regarding this matter.