Sending FIle with phone line

Its a bit hard given you havnt told us a whole lot here - for example, do you also have to supply the program/code for the recipient (on the other end of the phone line), or, are you only the client ?

If you are only a sender/client, then what file/transfer protocol does the receiver/server expect ?

If this were me I'd be abstracting the design/implementation of my program so that the ability to send via modem, or ethernet or protocol x was 'plugable', ie, I'd be thinking in terms of interfaces - you hand an interface to the implementation of a particular send protocol to a 'send' method - this means that you could implement a test 'receiver'/server program locally on your pc to make sure you have the guts working correctly - testing using a modem, depending on the size of the file, data cost etc, could be expensive

To use a modem itself isnt that hard - you need to search for C# Serial communications, which should provide enough information on how to do things like initialise, dial, send data via the modem - as I said, if you abstract the send -> 'carrier' interface , you can model serial communications for example using a loopback on your own pc

'g'