I tried to boot ubuntu 8.10 (Intrepid) with USB Huawei E220 modem and it worked properly. But when I removed and plugged it again, it didn’t work as expected. The modem can’t detect properly. The dmesg says :

[ 918.669157] /build/buildd/linux-2.6.24/drivers/usb/serial/usb-serial.c: USB Serial support registered for airprime
[ 918.669218] usbcore: registered new interface driver airprime
[ 951.283634] usb 2-1: new full speed USB device using uhci_hcd and address 2
[ 951.443512] usb 2-1: configuration #1 chosen from 1 choice
[ 951.449996] airprime 2-1:1.0: airprime converter detected
[ 951.450199] usb 2-1: airprime converter now attached to ttyUSB0
[ 951.450309] usb 2-1: airprime converter now attached to ttyUSB1
[ 951.451516] usb 2-1: airprime converter now attached to ttyUSB2
[ 951.680562] usbcore: registered new interface driver libusual

It sounds like the device is not being switched properly from CD storage mode to modem mode. In this case, ubuntu loaded usb device as airprime. So, blacklist airprime solved the issue. I put “blacklist airprime” in /etc/modprobe.d/blacklist . And the result :

[ 350.552290] usb-storage: device scan complete
[ 350.558942] scsi 8:0:0:0: CD-ROM HUAWEI Mass Storage 2.31 PQ: 0 ANSI: 2
[ 350.559604] scsi 8:0:0:0: Attached scsi generic sg1 type 5
[ 350.677826] Driver ‘sr’ needs updating – please use bus_type methods
[ 350.710655] sr0: scsi-1 drive
[ 350.710666] Uniform CD-ROM driver Revision: 3.20
[ 350.710773] sr 8:0:0:0: Attached scsi CD-ROM sr0

Yeah. It works.