Can I put my contract o2 SIM from a HTC DESIRE into an iPhone 4?

I'm wanting to buy an iPhone and use the sim from my HTC phone. Do I need to buy a new sized sim card or any other cards for this phone or will it work with the old sim card?

If the sim is a standard sim you can't put it in an iphone, the iphone 4 takes a micro sim, i'm not sure what type of sim yours is but if it's a micro sim you can use it, if not you need to ask the network of your choice to send you one, they don't normally charge to send one out and it's a fairly quick process too.

  • Locked (on contract) iPhone 4s, can I put my sim into a Nexus 4? I have an iPhone 4S and it's on contract with AT&T. It has a mini sim card just like a Nexus 4 uses, so can I pop out the sim card, put it into a Nexus 4, and use it to test the Nexus 4 (with data and voice and all)?
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