Get the list of modems known to ModemManager. List of object paths of modem devices known to the system. Start a new scan for connected modem devices. Set logging verbosity. One of [ERR, WARN, INFO, DEBUG]. A modem was added to the system. The object path of the newly added modem. A modem was removed from the system, and is no longer available. The object path of the modem that was just removed. Array of object paths of all modems known to ModemManager.