my work version with China unicom/CMCC /dev/ttyUSB1 crtscts noauth nodetach usepeerdns defaultroute modem 460800 0.0.0.0:0.0.0.0 noipdefault
it's highly dependent on your modem implementation, I suggest set less options, and if possible check the modem's log. the ppp link setup proc, firstly AT command for pdp context LCP link setup, may along with auth, then the ipcp procedure to get IP address, please refer to 3GPP TS27.060 -- unsubscribe: [email protected] website: http://groups.google.com/group/android-porting
