Virtual Fax Devices
A virtual fax device is one that appears to exist to a user, but in fact has no corresponding Telephony Application Programming Interface (TAPI) line device associated with it on a fax server. A fax service provider (FSP) that supports fax transmissions over the Internet is an example of a provider that uses a virtual fax device. In this example, a physical fax device does not exist, only a connection to the Internet.
An FSP can present multiple virtual fax devices to the fax service if the provider exports the FaxDevVirtualDeviceCreation function. The fax service checks the FSP DLL during initialization for FaxDevVirtualDeviceCreation. If the function is present, the fax service allows the user to send and receive faxes using the virtual device. For more information, see Using a Virtual Device to Transmit a Fax.