Like the iPad, the iPhone 4 uses a microSIM rather than a regular version. This, of course, has its drawbacks - you can’t simply slip the microSIM into a regular phone if you want to change handsets. But what about compatibility with Apple’s tablet? Will the iPhone 4’s microSIM work with the iPad? And how do you get hold of a micro IM without stumping up for an iPhone 4 on contract?

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Let’s start with the bad news first: if you’re planning on getting an iPhone 4 and then slipping the microSIM into an iPad 3G to gobble up some unused data, or vice versa, you’re bang out of luck. Apple and O2 have both said this won’t work, which means you’ll need separate data plans if you’re planning on getting both devices. In Apple’s own blunt words, taken from its iPhone 4 FAQ: “Your iPad microSIM card will not work with your iPhone.”

Apple’s move to microSIMs has already caused plenty of consternation, with accusations being levelled at Cupertino about its singular and sometimes infuriating approach to what consumers want. Surely a standard SIM could be accommodated by the iPhone 4, saving everyone hassle? Apparently not. It’s this approach that infuriates Apple haters, but with 600,000 iPhone 4 pre-orders, Steve Jobs is clearly doing something right.

Now, if you don’t want to go through the hassle of changing contracts and getting yourself a new SIM, there’s a DIY approach. The circuitry on a regular SIM and microSIM is the same, it’s just the outer area which is different. That means you can trim around the gold area of the SIM in order for it to fit into an iPhone 4, or an iPad. This comes with a huge word of warning though: slip and you might find your SIM is jiggered and you need a new one from your network. Not to mention the fact it may not play nice when you slide into an iPad or iPhone 4. Check out YouTube for a raft of how-to clips that’ll help you find a way to make your existing SIM nice and slim. But if you're too lazy to do any sifting, we think this one's the pick:

If this all seems like too much hassle, then of course, you can always get a SIM only deal and pay upfront for an iPhone 4. This will cost a hefty £499 for the 16GB model, rising to a wallet-destroying £599 for the 32GB version. However, O2 has said it will offer micro SIM only packages, with prices starting as low as £15 a month for a 1- month deal, which'll bag you 300 minutes, unlimited texts and 500MB of data. The same package will cost you £20 a month if you want a 30-day rolling contract.

Orange, however, is not doing SIM only deals. Or at least it hasn’t announced any plans. 3 is rumoured to be offering packages, as is Vodafone. T-Mobile’s plans remain unclear at the time of writing.

So, what if you want to put your microSIM into a phone which takes normal size SIM cards? Well, you can’t just slide them straight in, but there is a way. O2 has confirmed it’s going to sell SIM converters - essentially plastic moulds which you stick your microSIM into so you can use it on a standard handset. There’s already a microSIM store online selling these converters for €4.99. Hopefully that’ll help assuage any fears that the switch to microSIM is looking like a real pain in the backside.

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