3G modem - performance
max 500kbps
http://www.junxion.com/opensource/linux_highspeed_usbserial
http://linux.derkeiler.com/Mailing-Lists/Kernel/2006-05/msg08602.html
http://forum.openwrt.org/viewtopic.php?id=15144
https://dev.openwrt.org/changeset/8549
https://dev.openwrt.org/browser/trunk/target/linux/generic-2.6/patches-2.6.22/601-usb_serial_endpoint_size.patch?rev=8549