Well, I managed to recognise what exactly was my winmodem, I got drivers, kernel sources, and compiled all.
Then I loaded drivers and tried to login with wvdial. This is the output I had:

--> WvDial: Internet dialer version 1.53
--> Initializing modem.
--> Sending: ATZ
ATZ
OK
--> Modem initialized.
--> Sending: ATDT908200020
--> Waiting for carrier.
ATDT908200020
CONNECT 46667
--> Carrier detected. Waiting for prompt.
--> Connected, but carrier signal lost! Retrying...
--> Sending: ATDT908200020
--> Waiting for carrier.
Welcome to 3Com Total Control HiPer ARC (TM)
Networks That Go The Distance (TM)
login: NO CARRIER
--> No Carrier! Trying again.
--> Sending: ATDT908200020
--> Waiting for carrier.
ATDT908200020

And here I finalized the program after a few retries. What is failing here? What it the exact role of a carrier? It doesn't seem to be drivers, but I'm sending all info I have.

kernel: 2.4.22.32mdk
drivers: slmodem-2.9.6

Thanks