Virtual Modem PRO Frequently Asked Questions

Q. I have followed the step-by-step instructions in the User Manual, however, I still cannot establish a client-server connection between the two virtual modems. Any suggestions?

A. Make sure that:

  • Both ends have Virtual Modem installed and configured. Virtual Modem PRO [Single License] allows you to install Virtual Modem on two computers.
  • Both serial ports are opened after connection is created and prior to establishing connection (you may use HyperTerminal to open a serial port).
  • IP address and the TCP port number are set correctly on both ends of the connection.
  • TCP port is not blocked either by your firewall, or by your ISP (Internet Service Provider). In order to check that, try to telnet the remote host on the TCP port you specified. Click Windows “Start” button and choose “Run” option. Type in “cmd” to launch command-line prompt. In the new window type the following: telnet remote_host_IP_address TCP_port_number, where remote_host_IP_address and TCP_port_number are correct values and match the ones you have set in your configuration settings. Click “Enter” and try to send anything from the remote port to see if you are connected.Additionally, Virtual Modem PRO requires that TCP ports 8888 and 8889 are available to be able to create connection configuration and establish the links.

Q. I’m constantly getting the “Modem installation failed” error message while creating a new modem. What’s wrong (I use Windows 2000)?

A. Please, check the presence of mdmgen.inf file in your installation directory.

Q. I’m getting the “TCP port XX is already occupied by another modem or network service” message. I don’t know what I’m doing wrong. Can you explain?

A. The reason why Virtual Modem PRO generates such error message is that the selected TCP port is already in use. Most likely that you have assigned this TCP port as a server port to the other modem. Alternatively, this port may be used by other network services. In fact, any other applications won’t be able to open a TCP port which is in use by a virtual modem. That’s the nature of TCP sockets architecture. Please, note that to be able to establish connecting, you need just one virtual modem on both sides. And any of these modems can be client or server.

Q. I’m having troubles sending faxes using virtual modems. What should I do to fix the problem?

A. First of all, make sure that your fax application finds virtual modem. The procedure actually depends on the application itself and may vary significantly. Secondly, assign the virtual modem port to your fax application. Lastly, whenever dialing out to the remote host, try to use commas instead of dots and semi-column. For instance, if the remote host has IP address set to and TCP port 5401, then the number you dial should be 192,168,0,1,5401. Currently, we have tested virtual modem fax compatibility with VentaFax, MightyFax, Snappy Fax 2000 and Windows faxing.

Q. VM PRO issues the “Unable to create virtual serial port, VSP bus driver may not be installed. Please, contact technical support” message each time I’m creating a virtual modem. How to fix this problem?

A. Please, execute “vsbsetup.exe” in the corresponding sub-directory of the installation directory (by default: C:\Program Files\Eltima Software\Virtual Modem Pro\). For instance, if you are using Windows XP, you can find this file in the “NT5” sub-directory.

Q. I cannot create virtual modem! I get the “Virtual serial port COMXX already exists” message. What’s wrong?

A. The virtual serial port you have selected in “Modem serial port” combo-box, is already used either by Virtual Modem PRO or other application. Please, select a different port.

Q. Are hardware signal lines (DTR/DSR, RTS/CTS, RING, ERROR, DCD, etc.) emulated in Virtual Modem PRO?

A. Yes, all signal lines are emulated and supported. Same as in real null-modem connection, DTR signal line of the first port is connected to DSR and DCD line of the second port, and RTS of the first port connected to CTS of the second port.

Q. Can I use Virtual Modem PRO with virtual machine (VMWare)?

A. Yes, virtual modems are fully supported by SoftIce and VMWare, however you may experience some delays due to the peculiarities of the virtual machine engine.