PPP & LTE card: How to access AT commands once interface is up?

[Adrian Gschwend]

(I've asked this question on the OPNsense board first, see
https://forum.opnsense.org/index.php?topic=9828.0)

I've set up a PC engines based GW which is running an LTE connection as
WAN interface. So far everything works fine, connection is up and seems
stable so far.

Due to my location and frequency bands used here in Asia, I got a Sierra
Wireless MC7430 mPCIe card.

Specs:

https://source.sierrawireless.com/~/media/support_downloads/airprime/74xx/4116237_airprime_mc7430_product_technical_specification_r8.ashx

AT command reference:

https://www.sierrawireless.com/resources/documents/mp/2130309_mp7xx_at_command_reference.pdf

The card works fine, however as soon as OPNsense takes care of the ppp
connection via MPD I cannot send any other AT commands to the card. What
I would like to have is some kind of "stats" interface where I can get
things back like LTE network configuration, frequencies used, signal
level etc.

For my card the AT interface is on /dev/cuaU0.2, all other interfaces do
not return anything on AT commands. And /dev/cuaU0.2 is busy as soon as
the connection is up.

Anyone has an idea how to do that for this particular card?

thanks

regards

Adrian