Don’t forget, the iPhone 5 GSM version needs a new Nano-SIM, it will not work with your existing SIM cardIf you managed to survive this morning’s pre-order and grabbed yourself a shiny new unlocked iPhone 5 direct from Apple, you need to start thinking about SIM cards. The iPhone 5 doesn’t have the traditional, ubiquitous Nini-SIM card like the iPhone 3GS, it doesn’t even have the relatively new Micro-SIM card like the iPhone 4 either -- it uses a brand new SIM card which is called the Nano-SIM.

The Nano-SIM is much smaller than even the micro-SIM; actually it is 40 percent smaller coming in at just 12.3mm wide x 8.8mm high and 0.67mm thick. The current iPhone 4S uses a micro-SIM which measures 15mm x 12mm x 0.76mm and the 3GS uses a Mini-SIM which comes in at 25mm x 15mm x 0.76mm thick. As you can see, the SIM card has seen some huge size reductions over the last few years; it started out the size of a credit card.

So what does it mean if you have a new iPhone 5 on its way direct from Apple? Your current SIM card will not fit, you need to contact your carrier now and ask them about an iPhone 5 Nano-SIM. They should be able to send you one on time for the arrival of your iPhone 5. In the UK, my carrier Three already has them in-store and can activate it now. They provide the Nano-SIM card and SIM adaptors which will enable you to put the Nano-SIM card back in your iPhone 4S as a Micro-SIM or even your iPhone 3GS as a Mini-SIM too. This is the most reliable route as you have the Nano-SIM all ready to pop into your iPhone 5 as soon as it arrives.

Don’t forget about this or leave it too late as you may end up with a brand new iPhone 5 sitting without any service which would be extremely frustrating!

Of course if you ordered your iPhone 5 directly from your carrier, they should send out a Nano-SIM with your iPhone 5.