Can you provide a WHQL-signed version of the driver?

Unfortunately, it is not possible for Callback Technologies Inc. to provide the drivers certified through the Windows Hardware Compatibility Program for architectural reasons. Most of the business logic of any software that uses our products lies on the side of that software (a "controller process" as we call it). The testing and certification process involves a large number of tests conducted by automated software on a driver that is loaded by the OS. Such a driver is loaded in an environment that does not include a running controller process. The lack of the controller process means that depending on the product and the type of the OS request, the driver will either report success without doing anything or will report an error, leading to the "failure" of the test.