Problem with external modem after installing Ubuntu

[Savage]

Hi to everyone.
I have just installed ubuntu hoary and everything went fine, except that 
I can't connect to Internet. The problem is in my modem. I have a 
externall 56k rockwell modem connected on com1 or /dev/ttyS0.
I tried to set up a connection in "Administration -> Networking" but 
it's not all ok. The program autodetects it but everytime I try to 
connect the modem opens the line (i can hear the pulsating sound) but 
nothing happens. The modem does not dial. It's like when I have "Wait 
for dial tone" checked in windows. Is there any similar option that I 
can turn off here.
It's very important to me to fix this because I can't install any 
packages without Internet and this is the only way I can connect to it.
BTW the modem is Planet ME-560R externall modem and it's recognised like 
"Rockwell 56000 externall modem PnP" in win.

Konstantin Dimitrovski