I have a list of phone numbers, some of them are valid and some of them aren't. I have to write a simple program, which will check which phone number is valid and which isn't.
I thought to use SerialPort for this, but how can I disconnect directly after the first beep (before somebody answers the phone) or after I got message from the carrier that the phone number isn't valid?
Or may be there is some other way to solve it?
Thanks in advance