Phones come and go, but for the foreseeable future we will rely on those little SIM card thingamajigs to let the cell phone know which mobile number it is attached to. Of particular interest to me, and therefore the reason for this blog, is SIM cards that enable global roaming.
But seeing as this is my first post, I think it would be appropriate to define what a SIM card is:
- SIM is acronym that means either subscriber identity module or subscriber identification module
- It has a unique serial number, and internationally unique mobile phone number, and 2 passwords - a PIN for you and a PUK for the network
- It can store phone numbers, text messages and other data
- When it was invented in 1991 it was the size of a credit card. Then it became mini, and lately it micro, measuring just 15mm x 12mm.
I predict that the next iteration will be a small block, not unlike a USB stick, that snaps into place and doubles as the memory.
Here’s a picture showing the 3 types of SIM cards, and how they have become smaller:
