Hey, the plug on the bottom of the slice is the data cable outlet. The data cable allows the transfer of files to and from the Slice. Sadly, Virgin Mobile has yet to release the data cable for the Slice, but you can buy it from other retailers on the internet. I have read in other forums that people purchased this data cable, hooked it up to their computer with the phone, but there were no drivers that were available to read the phone's software. Plus, people who did find the correct driver for the phone still couldn't transfer files because Virgin Mobile locked the Slice from being able to do file transfer. I hope I answered your question!