ip config?
my 3G dongle on linux looks like it is successfully authenticating and then immediately dropping on ip config.
Jun 4 10:14:12 x pppd[3749]: CHAP authentication succeeded
Jun 4 10:14:12 x NetworkManager[873]: CHAP authentication succeeded
Jun 4 10:14:32 x NetworkManager[873]: <warn> pppd timed out or didn't initialize our dbus module
Jun 4 10:14:32 x NetworkManager[873]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) scheduled...
Jun 4 10:14:32 x NetworkManager[873]: <info> Activation (ttyUSB0) Stage 4 of 5 (IPv4 Configure Timeout) started...
Jun 4 10:14:32 x NetworkManager[873]: <info> (ttyUSB0): device state change: ip-config -> failed (reason 'ip-config-unavailable') [70 120 5]
Jun 4 10:14:32 x NetworkManager[873]: <info> Marking connection '3 - Internet' invalid.
...
Jun 4 10:14:32 x pppd[3749]: Connection terminated.