Is there a hidden config option that will reliably force the device to 3G and above, making sure it never connects to a 2G network? It’s not that my life depends on it, but the built-in insecurities of 2G have created some buzz in the media lately.
The only solution I’ve heard of so far is that Android 12 does it “on certain phones” and “on modem level”, which probably means the answer to my question regarding Sailfish is a no. But anyway… I’d like to ask those who are smarter than I am. 
According to this (via this post) there are configuration values for that.
While excellent in details compared to many other posts on the internet, that EFF article still leaves me with some questions. GSM can run A5/3 and A5/4 crypto, at least the latter of which should be just fine, but might be that it is rare in reality. And as they say between the lines 3G/UMTS isn’t that much better in the authentication department (they have the same-ish core network after all). With prefer 4G/LTE already being a thing, I’m not entirely sure what the improvement is. (although that is not really viable for us until we get VoLTE)
If my repo-sloughing serves me right, the radio HAL version mentioned in the article is not something that SFOS supports though (understandable, with it being an Android 12 thing). But i wonder what the difference there is compared to current possibilities.
Edit: some sort of insight to the change in 1.6:
https://android.googlesource.com/platform/hardware/interfaces/+/master/radio/1.6/IRadio.hal#349
They are changing from preferred to allowed apparently, not that i understand how the modem would ignore the preference with anything less than CSFB, if even that.
This app used to allow me to force 4g when I needed it with a slight tweak (during 4g rollout 4g data was unlimited/free while 3g not): https://github.com/JanneEdelman/radio-switcher
But not sure if the underlying mechanism hasn’t changed since then (app was abandoned during sfos 1.x when they added native 4g support, forcing 4g at the time did cause your phone to respond with busy signal when called)
From what I understand, you’d lose the ability to make (and possibly receive) voice calls, since Sailfish does not have a 4G telephony stack/VOLTE yet (though it is in the roadmap for 2022). Everytime you make a call it has to drop to 2G.
Not really correct. You drop to 3G or 2G depending on what your operator that has configured. But unless you are really familiar with the configuration in your area, and don’t travel much, it is probably a bad idea all the same.
Hopefully we get VoLTE soon, then a 4G only mode will really make sense.
Thx attah, but this is really a bit above my head. I was hoping for a config file in /etc that would contain a “disallow 2G” feature.
It drops to 3G here, so that wouldn’t be a problem.
The problem is that more and more operators are decommissioning the 3G networks to reuse the frequencies for 5G/NR. Thus, with the actual features of SFOS, disabling 2G and using an operator that has decommissioned 3G would imply sacrificing the “classical” voice service.
Having said that, I would support such feature. In fact, it should not be that complicated to implement.