error 650/dial up adaptor

I have the following problem which prevents me getting on
the internet.

i am using a tiscali USB modem in france, or attempting to.
it seems to want the asdl link to have a number it is
dialing from...

The modem works correctly, both lights on it are green and
the Saga Modem
(it is a Saga 800-840) shows a green light in the task icon
bar.
However, when I try to connect, I receive the following
message:
Error 650. And an explanation that my server type maybe
configured
incorrectly.
I have already attempted to do the following things:
re-install the modem.
re-install the dial-up connection
uninstall dial-up networking from windows (i am using
windows me) and then
reinstall it.
checked that the dial-up adaptor and the TCP-IP are
configured correctly.
Check my network settings.

what else should i do?