1: I have the sources of the modem drivers. They need to be compiled so that they will work on Fedora 18.
Normal modem drivers will recieve data at 56k and transmit at 42k
2: IF POSSIBLE, modify the drivers, so that the transmit = 56k and the recieve = 42k
I will ship you a modem so that you can test.
Tell me if 2: is possible to do.
Let me know for how much you are willing to do this.