wp8.1 OTGNawzil, whom many trust as a person with reliable Microsoft sources, has teased USB OTG or USB On The Go support coming with Windows Phone 8.1. As mentioned in tweet, once connected with a USB mass storage device, it will inform “USB storage detected, tap to view files”. Tapping on the message will open file manager which will show files. This feature will be welcomed like crazy by hordes of users coming from platforms like Symbian and Android.

As our Windows Phone 8.1 changelog page mentions,

Windows Phone 8.1 is certainly proving to be a huge OS overhaul than some mere cosmetic changes and nearly all settings, start screen and native apps have some changes to report.

Source