Telit AT Relay Service support has been added to libqmi mainline through MR!365 “libqmi-glib,qmicli: add Telit AT Relay Service (ATR)” and will be available since version 1.34.
What is Telit AT Relay Service?
The AT Relay Service is a custom Telit QMI service that allows sending AT commands through the mobile broadband interface (being it rmnet or MBIM through the QMI-over-MBIM feature).
This is particularly useful for those setups (both USB and PCIe) which don’t show dedicated AT channels, since it allows to continue using AT commands: some custom features are in fact implemented just through AT commands, not having a related QMI/MBIM request.
On the modem side, Telit ATR is currently supported in high-cat modems (FN990A40, FN990A28, FN980, LN920…).
qmicli and ATR
Considering ATR, qmicli exposes three actions:
atr-send: for sending the AT command and waiting for the reply
atr-send-only: for sending the AT command without waiting for the reply
atr-monitor: for listening to indications available on the AT channel
Note that, when using the proxy, these actions can be run also along with ModemManager running.
As usual, thanks to Aleksander Morgado for the review and useful advice!
Check out also how Telit FN990 is supported in Linux and ModemManager.