Just bought a iphone from Ebay and its unlocked and will want to put my o2 pay as u go sim card in and im on unlim texts and Web and wanted to know if i can just put the sim card into it or are there special ones for iphone?

Which iPhone is it? If it is the iPhone 4, then you'll need a microsim (available for free from O2 stores)

Or you could cut your existing SIM card

If it's an earlier iPhone your existing SIM card should work fine.

Nope its not iphone 4 its the the other phone.

Then your existing SIM card should work fine in it.

Many thanks