O2 Micro Sim
With an O2 micro sim deal being a plan that does not come with a handset, it is safe to call it a pay as you go sim deal. Just like other sim plans, O2 offers O2 micro sim deals either on a rolling monthly plan or a 12 month contract.
If you wish to have a rolling monthly O2 micro sim card with your iPhone 4, you have deals to choose from. One costs only £25 a month and comes with 600 minutes, unlimited texts and 500MB of data allowance.