Well I just purchased one and I can shed some more light on how to get it open. Start with the ends and gently pry up the plastic with a small screw driver inserted into one of the various openings so you can lever the plastic end cap up enough to slide a credit card between the end cap and the top and bottom plastic. Slide the credit card along and it will release the retaining plastic clips as it goes. Once both ends are off then you need to do the same for the top and bottom EDGES, same deal small screwdriver then the credit card. Now you will find 5 screws, remove these. Now if you look at the back cover where it wraps over the end caps gently pry up the retaining plastic clips that are built into the bottom cover then again credit card and work your way around. Think of the back cover as having little plastic fingers with a little retaining ridges that grab over the edge of the end cap and top and bottom edges as well. Hope this helps. Looking at where a sim card is designed to go with a strong light it looks like the circuit board was designed to have a soldered on connector. I count what I think is 9 solder spots but cannot be sure without taking the circuit board off to look at it but would seem reasonable as in the first page of instructions with mine it talks about installing a sim card if you have one, and a data plan before turning on the tablet so for some market somewhere in the world it must be offered I just dont know where that market is. I am in Canada and its not offered here, I would guess Southeast Asia or Australia maybe.