What you see in the image above is the evolution of mobile phone SIM card design over the past four years. The largest in the image, known as the mini-SIM, was used for quite a while as the standard in GSM cell phones. However, as smartphones began to rise in popularity, drop is cost, and brought increased functionality, it was determined that the mini-SIM just wasn't mini enough. It took up too much of the precious real estate that mobile phone manufacturers needed for other things. Thing like a GPS radio, Wi-Fi, larger batteries, dock connectors, graphics chips, and more. And so began the start of the shrinking SIM card.