Former Microsoft employee Nawzil Najeeb is claiming that his device running Windows Phone 8.1 recognizes USB connections to the handset, which means that it supports USB on-the-go.
"USB Storage detected. Tap to view files." Tapping on it opens the File Manager and shows the files. USB OTG on #WindowsPhone8.1— Nawzil (@Nawzil8) March 14, 2014
"USB storage detected. Tap to view files," is the message that appears when he plugged in a USB thumb drive to his Windows Phone using a USB OTG (on-the-go) cable. This looks like good news for those that are hoping to be able to access the file system in Windows Phone too.
Having USB OTG support does open up a lot of functionality to Windows Phone. In addition to external storage devices, we could see all sorts of accessory support.