I can't remember where these came from… and now I cant find that page, so here they are

/etc/ppp/chat-o2

TIMEOUT         5
ECHO            ON
ABORT           '\nBUSY\r'
ABORT           '\nERROR\r'
ABORT           '\nNO ANSWER\r'
ABORT           '\nNO DIALTONE\r'
ABORT           '\nRINGING\r\n\r\nRINGING\r'
''              \rAT
TIMEOUT         30
# this next line is extra for O2
OK              AT+CGDCONT=1,"IP","mobile.o2.co.uk"
OK              ATE1
OK              ATD*99***1#
TIMEOUT         30
CONNECT         ""

/etc/ppp/peers/o2

/dev/ttyACM0
56700
noipdefault
usepeerdns
defaultroute
persist
noauth
connect '/usr/sbin/chat -v -f /etc/ppp/chat-o2'

Once you have those in place plug in your phone via usb (you can use bluetooth plus rfcomm I think) and select the PC suite mode on the phone. Then run “pon o2” to start it up and “plog” to see what's happening. You should see a connection being established, getting an ip and dns servers. In my experience it doesn't work everytime, you may have to do “poff” disconnect the phone and try the process again once or twice before it works.