SIM cards, short for Subscriber Identity Module, are little pieces of plastic that determine your phone number, your plan and carry identifying information about the owner of the phone. They are rather like license plates to a car, the thing that makes all the hardware eligible for use.
When mobile phones were first invented they didn’t have SIMs. All user information was stored directly in the phone itself. Some CDMA phone still use the same system. But this made it really hard when it was time to change phones as all that data had to be re-programmed into the new hardware. Interchangeable SIM cards made the job a lot simpler.
But now instead of one standard size for all phones, phone makers in their quest for smaller, lighter phones have started introducing SIMs in ever smaller sizes. Infact there is a strong push by Apple to go back to the original embedded SIM design of old, bringing back the control from carriers to handset makers. It may be sometime before we see that, but already the SIM is shrinking rapidly.
iPhone 4 was the first to require the micro SIM and carriers scrambled to oblige. The new size spawned a whole cottage industry dedicated to converting standard SIMs to a smaller size.
The Micro SIM maintains the same memory and security features of a standard SIM despite ite smaller size.
Next phase, also pushed by Apple, was the even smaller Nano SIM for the iPhone 5 that did away with all plastic surrounding the smart chip. Not surprisingly more phone and tablet makers are following the lead. Now we have Combi SIMs and adapters that can be popped out of a frame to match the device requirement.
Are we getting ever closer to ‘embedded SIMs’? Most likely yes. Carriers will fight tooth and nail before handing over control to device makers. But that seems to be where the future lies.