3gpp-set-eps-ue-mode-operation fails to set some options

[Aleksander Morgado]

Hey Brendan,

> I'm trying to use the `--3gpp-set-eps-ue-mode-operation` to set `data-centric` or `voice-centric` modes.
>
> I note there are 4 possible values: ps-1, ps-2, csps-1 and csps-2, with ps-2 and csps-2 being data-centric.
>
> My Quectel E21 modem only accepts one option; csps-2.  All other options fail.
>
> What determines what options MM can or cannot set for ue-mode ? - is it the modem, SIM card, network, other?
>
> How can I use the `--3gpp-set-eps-ue-mode-operation` option to set/change from voice-centric to data-centric, etc.
>
> I would prefer not to issue AT commands (especially since Debian does not configure MM to allow AT commands and I have to use debug mode).
>

The EPS UE mode of operation implementation is currently only
implemented using AT+CEMODE, so if that's failing to set some of the
options, it's because the modem is rejecting them in the +CEMODE call.

I've recently discussed about this with @Reinhard Speyerer in some
emails, and he pointed out there's also now AT+CEUS applicable to both
4G and 5G; and he also pointed out that there are some QMI TLVs we
could use in the "NAS Set System Selection Preference" to configure
the same settings as +CEMODE and +CEUS. At some point I think we need
to extend the API with a new method equivalent to +CEUS and still keep
supporting the +CEMODE based one.

We're in the process of adding a lot of new 5G related APIs, so if
anyone wants to work on defining new APIs that would fit all this in a
better way, that would be extremely appreciated.


--
Aleksander
https://aleksander.es