This was tested at an embedded system running Ubuntu Core.
Create an udev rule ”/etc/udev/rules.d/45-huawei1550.rules” with the following content:
SUBSYSTEM=="usb", ATTRS{idProduct}=="1446", ATTRS{idVendor}=="12d1", RUN+="/usr/sbin/usb_modeswitch --vendor 0x12d1 --product 0x1446 --type option-zerocd"
make it executable:
chmod +x /etc/udev/rules.d/45-huawei1550.rules
From now any time a USB modem is inserted into a USB connector this udev rule will run and disable a flash drive on the USB modem.