USB GPRS

Purpose

Get external USB 3G HSDPA GPRS Modems to work with the Nokia N800 (or newer).

Enable USB host mode.
get a powered USB hub.
connect your Nokia N8x0 to the USB hub's uplink.
connect your USB Modem to one of the USB hub's normal ports.
switch your Nokia N8x0 to USB host mode ("echo host > /sys/devices/platform/musb_hdrc/mode").
compile a SCSI generic Linux kernel module (or download a binary module from CDROM Kernel Modules ).
load the SCSI generic Linux kernel module: "insmod sg.ko".

compile the "HSO" Option Modem kernel module (Greg Kroah-Hartman is in the process of integrating the kernel module into the mainline kernel, but check HSO in the meantime or use my working directory (includes compiled modules) Nokia N8x0 Modem) for the Nokia N8x0.
compile the Rezero Option mode switch application.
run the Option mode switch application: "./rezero /dev/sg0".
load the "HSO" kernel module: "insmod hso.ko".
edit the "connect.sh" script (from HSO) to actually do the changes in the routing table.
run the "connect.sh" script: "./connect.sh up".
enjoy.

Alternative (generic?) mode switch program http://www.draisberghof.de/usb_modeswitch/

make a ready-to-use Debian package.
use the udev script to automate the loading when the device is plugged (both for "rezero" and for "HSO").