It may be usefull to add interface for sending arbitrary AT commands via mmcli/dbus. For example, for QMI modems there is no possibility to send USSD requests. While not implemented, it's not so hard to send them manually, but command port already used.
There's already that support, but only if you run ModemManager with --debug (i.e. it's only for debugging purposes). Will mark it as wontfix, because opening a backdoor like an AT interface while ModemManager controls the logic of the modem is not a good idea. BTW, the correct fix is to implement USSD support in QMI :)
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