VSPD.net

Network Virtual Serial Ports Driver is an advanced utility, the purpose of which is to emulate null-modem cable on computers located in a TCP/IP LAN or connected to the Internet. In other words, with VSPD Net you can create any number of pure virtual serial ports in your system, which will be connected over TCP/IP network to another computer via virtual null-modem cable.

Real serial ports will not be occupied.