Some phones now use a micro sim. Like iPhone 4, iPhone 4S, Nokia Lumia 800 and Samsung Galaxy SIII.
When you buy a new phone from us, we'll give you a micro sim if your need one.
But if you're an existing O2 customer and want to get a micro sim in advance, you're in the right place. Just fill in the form and we'll post one to you.
Once your sim arrives, visit our simswap page to find out how to swap your current standard sim to your new micro sim. There's no need to call us.