MIC Gadget - The next iPhone? We are not sure, but we’ve just got our hands on an engineered prototype of iPhone 4, with 64 GB storage capacity. We tested it, and it is the real thing, no jokes here. On the back of the device, it has “XXGB” marking, representing the unit as potential Apple prototypes. However, we found out that the device is very similar to the lost iPhone 4 prototype bought by Gizmodo. We have a video and some photos for you to take a clearer look at it.