Usbserial a generic serial driver
This driver is the standard USB serial interface driver that is used when there is not a dedicated driver available.
Essentially you can bind any USB serial device to this driver if you use the right commands. Performance is often reported as being lower that say the option.ko driver which is optimised for 3G networks.
If you have a 3G modem not supported by option.ko, nozomi.ko or hso.ko then you can use this driver
usbserial vendor=0xaf0 product=0x6500
The example above makes GTM351 module work with the the usbserial driver. The vendor and product IDs are identified by using the following command:
lsusb -v
and searching for the Option device.
Other examples of Option product codes are listed in the old product table.