Virtual Modem
There are many old data-centric applications that, for historical reasons, use direct modem connections to exchange data between Client and Server. Nowadays, local and global TCP/IP networks have made the direct modem connection obsolete. Here's why: When you use a direct modem connection, you... The application can control the virtual modem directly by sending AT commands or with TAPI (MS Windows Telephony API). ... Thus, Virtual Modem should work out-of-the-box for all your communication programs.
http://www.virtual-modem.com/virtual-modem.zip - 737Kb - Download - Screenshot

Virtual Null Modem
Null-modem cable is basically used for communication of two RS-232 DTE devices with each other. To create null-modem connection between the devices you need to use two computers or two serial ports of a single computer connected with null-modem cable. ... The most reliable way to create null-modem connection is using of virtual serial ports emulated by virtual serial port driver and null-modem cable. ... Virtual null-modem allows user emulate virtual null modem connection and run the two applications simultaneously on the same computer.
http://www.virtual-null-modem.com/download/vnullmod20.exe - 1Mb - Download - Screenshot

Virtual Serial Port Driver XP4.5
Virtual Serial Ports Driver XP creates two pure virtual serial ports in your system which are virtually connected to each other. For other Windows applications, virtual ports will be seen exactly as two real serial ports connected via null-modem cable. ... Virtual link between virtual serial ports is much faster then real null-modem cable connection and depends on your processor speed. ... With user-friendly GUI and on-the-fly help of Virtual Serial Port Driver XP it's very easy to configure a virtual serial ports pair.
http://www.mks.zp.ua/vspdxpd.exe - 1Mb - Download - Screenshot

ModemTest
ModemTest is an easy to use Windows based application that allows users to test their dial up modem. ModemTest performs low level testing that is independent of your Internet Service Provider (ISP) and the TCP/IP settings on the computer. It allows the modem to be tested in addition to the phone... A local loop back is done on the analog side of the modem, ModemTest then sends data packets which are echoed back by the modem. ... The second test method requires only a single modem and no telephone line.
http://www.passmark.com/ftp/modemtest.exe - 386Kb - Download - Screenshot

Virtual Serial Port Kit
Virtual Serial Port Kit creates pairs of virtual serial ports in your system which are virtually connected to each other. Physical null modem cables are not required. You can connect any number of virtual port pairs. Virtual serial port pairs will look and work exactly like real hardware serial... Virtual Serial Port Kit is useful also for users which work with Windows applications using serial COM ports joined by null modem cable especially if those applications require more than one serial port pair.
http://www.virtual-serial-port.com/virtual-serial-port-kit.zip - 796Kb - Download - Screenshot

DEKSI Modem Pooling
DEKSI Modem Pooling (DMP) is an advanced, powerful, and feature rich client-server software system that allows you to use any serial (COM) port on a remote computer from your local computer via a TCP/IP network connection. Sharing COM ports means sharing resources like modems, ISDN adapters, X. ... DEKSI Modem Pooling needs to run the Server software on the server computer to accept and route data from the virtual port to the physical port on the server computer. ... DEKSI Modem Pooling consists of two components: The Client Component (DMPC.
http://www.deksoftware.com/new/dmp.zip - 2Mb - Download - Screenshot

Advanced Virtual COM Port
Advanced Virtual COM Port is the first software of its kind which includes both local and network virtual COM port functions. It can share your real COM ports or it can create virtual COM ports and connect them with a virtual null-modem cable locally or through a TCP/IP network or the Internet. ... Virtual serial ports created by the program look and work the same way as real ones look and work. ... You can connect to a shared port and use it just like it is on your machine.
http://www.advancedvirtualcomport.com/files/AdvancedVirtualComPort.zip - 1Mb - Download - Screenshot

Virtual Serial Ports Driver CE
Virtual Serial Ports Driver CE creates up to 20 pure virtual serial ports in your mobile system, this results in up to 10 virtual serial ports pairs. Each pair has 2 ports that are virtually connected to each other. For other applications, virtual serial ports will be seen exactly as two real... In this case all data sent by other applications to virtual serial port COM5 (VSP0) will arrive at virtual serial port COM6 (VSP9), and all data sent to virtual serial port COM6 will arrive at virtual serial port COM5 (VSP0).
http://www.eltima.com/download/vspdce.exe - 432Kb - Download - Screenshot

MVP Checkers
The classic game of Checkers has never been better. Six virtual opponents challenge you to a hot game of Checkers. Wonderful graphics and music provide the atmosphere as you take on a virtual opponent or challenge your friends to a Checkers "death match" over the net, LAN or by modem.
ftp://ftp.mvpsoft.com/pub/check10.exe - 2Mb - Download - Screenshot

Virtual Serial Port Driver XP4
Virtual Serial Port Driver XP4 creates two pure virtual serial ports in your system which are virtually connected to each other. For other Windows applications, virtual ports will be seen exactly as two real serial ports connected via null-modem cable. ... 0 you can connect one application to another using virtual serial ports pair. ... For example, you can create virtual pair COM5-COM6. ... You can select any port numbers for virtual pair. ... With Virtual Serial Port Driver XP 4. ... This solution can be used, for example, for GPS simulation programs.
http://www.virtualserialport.com/download/vspdxp.exe - 1Mb - Download - Screenshot