Hi there,

I'm using a Quectel EC21 with the GSM PPP driver. This works well so far. Now I would like to use SMS messaging and GNSS additionally. GSM MUX seems to be a good feature therefor. But I am wondering if this is currently intended to be used outside the zephyr modem drivers itself. It seems there is no public API to send AT commands to the modem. Studying the source of gsm_ppp.c the driver opens three different channels (control, ppp, and AT) and finally exposes the AT channel via the modem context `iface` member. But since "modem_context.h" is not public available there is no way to access the interface. Already noticed the issue here: https://github.com/zephyrproject-rtos/zephyr/issues/23887. It addresses the same problem except not for GSM MUX but sending custom AT commands in general. But should be pretty much the same issue. Unfortunately there has been no discussion for over 2 years now.
I'm confused on how to be able to deal with that pretty common use case. The easiest would be to import "modem_context.h" via ""../../../zephyr/drivers/modem/<include file>" as suggested in the issue even though the API is not meant to be public. Is this the only solution atm or am I missing something?

Thanks for any help.