Wired (USB) Connection to a Mobile Phone
 
This test was done using a Motorola A780 phone.  What follows should be similar for most phones that will act as USB modems.
 
Note: Make sure the phone is properly configured to access the internet on its own first.
 
Phone: Make sure the USB port is Modem mode: Setup >> USB Mode >> Modem
 
B1L: We need to edit 2 files.  Note that at least the first of these 2 is specific to the Motorola Linux based phones (E680i,  A780, A1200, etc.). Omit this step if using most other phones.
 
Open /etc/ppp/options in your favorite text editor. Add the following to the end of the file:
 
:192.168.0.254
(That's a colon at the beginning - Don't forget it.)
 
The second change is in  /etc/chatscrips/ppp0.  Comment out or delete the line that looks like:
"" "AT&F0M0"
 
(I am not even sure why that is even in there.)
 
B1L: Network Manager >> Manual Configuration >> Modem Connection >> Properties.  Enter the following:  (Example is for the New AT&T, North America)
General Tab
Phone Number: *99***1#
Dial Prefix: <leave blank>
Username:  WAP@CINGULARGPRS.COM
Password: CINGULAR1
Modem Tab
Modem Port:  /dev/ttyACM0    (You'll have to type this, it's not in the pull-down)
Dial type:Tones
Volume: Off
Options Tab
Set all 3 options ON
 
That's it.
Trouble Shooting :
Did /dev/ttyACM0 get created when you plugged in your phone?
 
Look for problems as the connection comes up:
tail -f /var/log/messages
 
Check for a ppp0 entry in ifconfig.  Is there a valid IP address?
ifconfig