Serial to USB Converter

I have a laptop with no serial port. I have recently acquired a CDMA phone
for use as a dial up internet conecction. The problem I face is that the
cable supplied with the phone requires a serial port on the computer. The
phone has an RS232 socket. There are serial to USB converter driver software
available but I am in India and the software is very expensive. Can anyone
help me on where I can get free drivers or shareware. I have a cable that
should be suitable- RS232 at one end and USB at the other.
Many thanks.

Shiv