so I am wanting to buy an Apple iPhone 4 16GB Black Factory Unlocked SIM Free No Network Logos.
http://www.amazon.co.uk/Apple-iPhone...153717&sr=8-24

I am unsure but what does it mean by SIM FREE? Does it take no SIM Cards, a smaller version or standard one? Third question, does the 3GS Iphone take a normal standard Sim Card or a smaller type?

Sim free phone means it is not locked to a network so will therefore take and network sim 3/tmobile/voda/o2/ ect

The iPhone 4/4s take a smaller sim card - so your current one, say out of a blackberry, would need to be cut down

The iPhone 3/3g/3gs all use a standard sized sim

I think u can get a sim card cutter and adaptor off ebay for a couple of quid

Thanks everyone for the replies. I'm glad I asked now. I feel a little more confident now about them.