Enumerating Available Fax Devices

To enumerate the available fax devices, the fax routing extension must read the registry. It is recommended that the fax routing extension open and read the following registry key during initialization:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Fax\Devices

The registry subkeys under this key are the fax devices that are available for the fax routing extension methods to use.

Each fax device has multiple registry values, but the value the fax routing extension requires is the PermanentLineId value. This value is a DWORD that contains the fax device identifier. The fax service passes this identifier when it calls the fax routing extension functions.

The fax routing extension should create a registry subkey to store persistent fax device configuration in the registry under the corresponding Devices key. An example of data specific to the fax routing extension could include file format configuration information for a particular fax device.

After the fax routing extension reads the registry it must create a table into which it copies the device identifier for each available fax device. The fax routing extension must also copy to the table all configuration data for a particular fax device that is specific to the fax routing extension.