updated 11:38 am EDT, Mon September 10, 2012
Could represent iPhone 5 units plus 8GB iPhone 4S
The UK branch of T-Mobile is listing four "iPhone X" models in its internal and external databases, notes 9to5Mac. The models are split into four different capacities, scaling up to 64GB. Of special interest though may be the 8GB model, since Apple isn't generally expected to introduce an 8GB iPhone 5.
The answer is likely that the unit is a version of the iPhone 4S meant to become Apple's new middle-tier device. The iPhone 4 would logically become Apple's bottom-level option, given away for free on contract, or at reduced cost when unlocked. Apple should reveal the new iPhone lineup at its Wednesday press event.