I'm trying to code a program that will dial a list of numbers (fax
numbers), and all I need to do is detect if they answered with a fax
tone, or if a voice picks up (line mixup) or if it's busy or fast
busy.

How do I determine each case?  I'm using an ocx/dll from
www.hardandsoftware.com called NETCOMM by{*filter*} Grier since there is no
native support for serial communication in .NET.

Any information will be greatly appreciated as I'm new to serial
programming.

Thanks!!!