Interaction with ModemManager

[John Whitmore <arigead gmail com>]

I could probably send this message to the ModemManager list as well but I'll
start here. 

I was on last week about connecting 2 4G LTE USB Dongles to a RaspberryPi. I
got one working but had a few issues with the second (vodafone) one. Every
time I edited the connection, the "vodafone" password had disappeared from the
connection. I'm away from the unit at the moment, taking a break 'till
tomorrow, then back at it. I ended up moving from Raspbian to Ubuntu Mate on
the RPi as Raspian has such old versions of NM and MM. Actually had serious
problems with Ubuntu Mate and Serial ports both the GPIO serial on the RPi and
USB - Serial cables. SO think I might be moving on the Arch Linux. There's a
first time for everything.

Anyhow that's not my question. When I'd added a dongle that was correctly
modeswitched and recognised by ModemManager I was able to create a new network
connection in the NetworkManager. My question is with regards to entering the
ISP details into the NetworkManager. If I'd an operator SIM, say "three" in
the dongle and create the network connection but then pull the dongle and
change the SIM to "vodafone" then the NetworkManager will attempt to connect to
the "vodafone" network with the "three" APN details.

Now I've not tested that and what happens so forgive my possibly premature
question. It seems more logical to me that the APN details would be entered
into the ModemManger and NetworkManager don't need to know it, but just
requests a connection from the ModemManager. Ideally the ModemManager could
look at the current SIM and say what that means in terms of APN details.

New to the party so I'm sure there's a good reason why it is the way it is,
but just wondered. I'm sure that the data required for a Data connection must
be on the SIM becasue if I have an open unlocked phone and insert any SIM I've
never been asked for APN details. Phone just knows what to do. Well that's
been my expierence.

John