Setting the Last-Error Code

The fax service provider functions return a Boolean value that indicates the success or failure of the function. If the function fails, the fax service calls the GetLastError function to retrieve extended error information.

When a function fails, the fax service provider must call SetLastError immediately to set the last-error code. If the fax service provider calls another Win32 function after setting the last-error code, that function can overwrite the fax service provider's last-error code.