No, it's not possible to update the WinFax application since no update is available. I've checked various download sites with hope to obtain the installation package, but I couldn't find anything for this purpose. Also, based on its release date (somewhere in 2006), I can say that the program is discontinued in percent of 70-90 %. There was a website, but it displays an error. I've checked then multiple times today and the message was the same.
