The Portable SIM, as Japan's Docomo is calling it, will combine your tiny mobile card with Bluetooth and NFC to make a standalone authentication device, allowing users to 'wave' the portable over tablets and smartphones to connect and login to phone networks, transferring information, like phone numbers and login details and opening up the possibility of multiple devices with a single SIM card. (Android and iOS, all at once!) It will even store multiple online logins for shopping sites and social networks, according to the Japan's largest phone carrier. The current prototype is around the size of a WiFi hotspot, although Docomo plans to shrink the tech down to a size that would fit into a wearable device, likely to be around the size of current wearables like Acer's Leap band we've used in the mock-up above.