They are using all sorts, like TurboSIM, etc, but most ppl are waiting for three months, to get the official onlock code from Orange, that is buy the code, based on your IMEI.
Seems Skate/OMC is a lost cause, and lost opportunity for Orange, and ZTE, being under-powered, over-sized, the Blade's fatter unfit big brother, too much curry and chips, and very much "last year"....I would say avoid.
Although, it is cheap to buy from Orange, £130 (incl. top-up).....+£20 to unlock 3 months from registration.
Although maybe, if you can root it, slim it down a bit, custom rom, etc, etc.
Whilst containing details for using an alternative sim from giffgaff (02 network piggyback) I think this video will show the underlying process. Says he who hasn`t even got his Android phone yet and not sure if I`ll end up with the San Fran II depending on stock levels and delivery from Orange or the Monte Carlo (in shop up to now).