O2 is to open its stores early on Thursday morning 24 June, at 8.02am, in order to serve existing customers who want to upgrade to the iPhone 4. The provider is not offering any pre-order or reservation service, and phones will be dished out on a "first come, first served" basis, according to a sales assistant at one of its London branches.

This comes as stock is expected to be in limited supply, with the company already telling new customers that they will have to wait until the end of July if they want an iPhone 4 with O2.

So, with O2 at least, it looks like queuing will be the only option on launch day. And, even if you're willing to cough-up particularly meaty sums of cash to buy out the remaining months on your contract and for the handset itself, you might still be left wanting.