[newbie] establishing a ppp connection

[s3x]

i seemed to have my modem (isdn bri t/a external) configured properly under
kppp and the account info is correct but it never finishes logging in.  when
i watch the log window all i get is garbage characters. i've tried every
setting i saw ( CHAP, PAP, Script and Terminal) to no avail. i've filled in
expected arguements and all. does anyone have a clue where i should start to
fix this.

your help is appreciated