Check if other programs are using your modem.
Fax software, Supervoice, etc...
Ctrl-Alt-Delete, and end task "RNAAPP".
Restart.
Try diagnostics on the modem, if they come up without a port already open error, it should be fine.
Uninstall and Reinstall connectoid, the network settings, pwl files, and DUN.
Uninstall and Reinstall modem if it persists.
Search for RNAAPP in the windows registry and remove any instances.
WARNING: This should NOT be done by a user, this fix should be done by a computer tech.