Após instalado o firmware certo do modem usb, o dmesg finalmente o reconheceu... até a velocidade da ADSL pegou certinho...
root@raulzito:/root/bkp# dmesg | grep ADSL
ATM dev 0: ADSL line: training
ATM dev 0: ADSL line: attempting to activate
ATM dev 0: ADSL line: channel analysis
ATM dev 0: ADSL line: up (2976 kb/s down | 640 kb/s up)
root@raulzito:/etc/ppp# pppd call gvt
pppd 2.4.4 started by root, uid 0
Using interface ppp0
Connect: ppp0 <--> /dev/pts/3
Modem hangup
Connection terminated.
pppd[4210]: Exit.
# Aqui as confs...
root@raulzito:/etc/ppp# cat peers/gvt
user "turbonet@turbonet"
plugin pppoatm.so
noipdefault
usepeerdns
defaultroute
persist
noauth
nopcomp
noccp
novj
root@raulzito:/etc/ppp# cat options
asyncmap 0
auth
crtscts
lock
hide-password
modem
proxyarp
lcp-echo-interval 60
lcp-echo-failure 4
noipx
#replacedefaultroute
noipdefault
#noauth
persist
lcp-max-configure 50
-pap
name any
user "turbonet@turbonet"
defaultroute
plugin /usr/lib/pppd/2.4.4/pppoatm.so 0.35
root@raulzito:/etc/ppp# cat chap-secrets // O pap-secrets ta igual...
# Secrets for authentication using CHAP
# client server secret IP addresses
"turbonet@turbonet" * "gvt25"