How Can I connect a Punching SYstem to a network and access it as a Local COM Port?

I have a Time & Attendance Punching System and the software included only allows me to choose Local COM Ports (COM 1, COM2, etc.) it doesn't let me choose other ports. The Punching system uses a standard telephone line with a RS232 Adapter at one end. I found a way to connect the Punching System to my Network using a RS232 Ethernet adapter (http://www.industrialethernet.com/net232-dte.html). I think there is another way using an Adapter that attached to the telephone line and converts ir to Ethernet but I have not found any details on this. Can someone orientate me on which way is the best and how should I do it