The port handle is invalid.
This is a fairly common modem error message.
This can be causesd by new/old modem drivers you just installed or more
frequently this is caused when you placed in a new invalid init string for
I would suggest taking that init string out first, and just putting in
AT&F or AT&F1 to start to return the modem to the factory settings.
Rebooting is also a good idea to clear everything out, especially if you
are playing with init strings.
If you just installed new modem drivers and received the error, reboot and
try again, and if need be, uninstall/reboot/reinstall using older known to
be good modem drivers.