iPhone MTP USB Device driver for iPhone not working. Hi Guys. I currently own an iPhone 5S and I have Windows 8.1 PRO x64 installed on my PC. PC fails to detect iPhone 7, 6s, or other Apple mobile devices via USB cable ... installing MTP USB driver or Apple Device USB driver. MTP stands for Media Transfer Protocol, which Microsoft uses to allow access to files (like photos and videos) on iOS and Android devices.