I am using debian Wheezy
Linux 2.6.32-5-686


#aptitude install usb-modeswitch
#aptitude install wvdial

edit the /etc/wvdial.conf

[Dialer defaults]
Phone=*99#
Stupid Mode=1
Dial Command=ATDT
Modem=/dev/ttyUSB0
Baud=230400
Init2=AT+CGDCONT=1, "IP", 3gdgnet"
Init3=
Username=digi
Password=digi
AskPassword=0
ISDN=0
Compuserve=0
Force Address =0
Idle Seconds=0
Auto DNS=1
Check Def dRoute=1

plug in the Huawei E220

#wvdial