The modem worked fine after I added the package, FLDIGI (ham radio program), and
afterward surfed the web, etc. Now I can't connect via the modem. I hate to
remove the package as I use dial-up and it took a long time to download, I'd
sooner reinstall the older version of UBUNTU.

I tried sudo ifdown ppp0 as suggested and got "unable to resolve local host"

I tried the wvdial suggestion and got an error message with that.

As I said before, v6.06 worked fine, why did they have to change it?