i've been trying for a couple of days to get the speedtouch 330 dsl modem to run under linux and finally i got successful
so here it is
lock ipparam "adsl" defaultroute noipdefault usepeerdns noauth holdoff 4 maxfail 25 persist asyncmap 0 user "xxxxx" name "xxxxx" plugin /usr/lib/pppd/2.4.2/pppoatm.so 8.35
"fti/xxxxx" "*" "votrepasswd" "*"
PEERDNS=yes
/sbin/modprobe pppoatm /usr/sbin/pppd call adsl
and so it worked
note that if there is a pap-secrets file login will fail, if after the modem is pluged in the usb and the two leds are not blinking while the phone line is not pluged then the modem is not initialized and maybe you have the wrong firmware or it is in the wrong location or maybe you need the modem_run package but i think it is in the distro
good luck . . .