[Feature Request] improve options for choice of network

Currently, in my city the 3G network is dismantled. This leads to the situation, that I have very shaky connections with 3G and the phone sometimes switches to 2G during calls, which is accompagnied by disturbing noises.
I would like to have the option to restrict the network for calls to 2G (which has fine and reliable coverage) while 4G is allowed for data connection. Would it be possible to implement this easily as long as VoLTE is no option?


No that is not possible.
The network decides where you are sent when doing CS-fallback from LTE to make/take a call.

Actually I do not understand your statement. Obviously the phone module is able to use a different connection than the data connection, otherwise I could not use 4G at all. On the other hand it is possible to restrict the phone to 2G (together with data connection). So why is it technically impossible to ommit 3G connection for the phone. This seems illogical to me. Could you explain your answer further, please?

You can already choose “Prefer LTE” for the data SIM and “2G only” for the other (voicecall/messaging) SIM. That’s pretty much what you want, right? At the moment you can’t lock data SIM at LTE (e.g. prevent switching technologies) but that may become possible in not so distant future, provided that your modem supports it.

And unfortunately I don’t see “LTE and GSM only” option in the low-level modem API:


Looks like you can’t ignore WCDMA (3G) without ignoring either LTE or GSM (2G) along with it. I have no idea why.


Probably I could if I had a dual SIM phone, but I have a single SIM device. I should have included that in my original post, sorry.

In my mobile network settings I see for every SIM card:
Prefer 4G, prefer 3G, only 2G.

This makes sense, you can force the phone to use a lower level network than available.
I had the situation, where 4G is available but did not work because of bad receiving conditions. So the phone did log in to the 4G base station but did not work. No internet connection possible despite the 4G symbol on display.
After manually switching to 3G only, internet connection worked fine with 3G at the same place + receiving conditions.

Except for dual-sim (where it is sometimes even required) you cannot be connected to two technologies at a time.

When you are on 2G/GSM or 3G/UMTS, that’s your data connection. When you try to place a call when connected to 4G/LTE (and not registered for VoLTE), that network drops you off to a (often manually) preconfigured fallback cell in that area that can handle CS-voice, i.e. 2G or 3G.

So if theoretically your phone could claim to support only 2G and 4G (which is perfectly valid on the air, as i understand it), you’d have to count on that your operator having configured fallback cells for both technologies. Since it is pretty much unheard of to have a phone that supports 4G and only one of the two others, i’d be surprised if your operator had bothered doing that. Heck, the base station manufacturer might not even have seen that as realistic and only let them configure one fallback or one type of fallback at a time.

Given this, it is probably a good idea that the modem (or at least this interface to it) also doesn’t consider it valid, since the effect would just be you being dropped, and/or not even notified at all.

Dual SIM does work like that, I can confirm…