GSM_MUX send AT commands to modem

[ivonalo]

Hello everybody, I am using muxing on my modem with the CONFIG_GMS_MUX = y enabled. I want to have both PPP interface up and send AT commands to the modem. I have successfully started muxing and ppp with CONFIG_MODEM_GSM_PPP = y. Now, while the PPP interface is up I want to send periodically an AT command to the modem, to ask for the GPS coordinates, but I am not sure how to do that. Can I do it from my user code or must I edit the gsm_ppp.c file directly and add my AT commands there?
There is no example available and I am not sure how to claim the CONFIG_GSM_MUX_DLCI_AT channel from user code