This driver supports USB modems and ISDN adapters which support the
Communication Device Class Abstract Control Model interface.
Please read Documentation/usb/acm.txt for details.

If your modem only reports "Cls=ff(vend.)" in the descriptors in
/proc/bus/usb/devices, then your modem will not work with this
driver.

To compile this driver as a module, choose M here: the
module will be called cdc-acm.

source code:

drivers/usb/class/cdc-acm.c