But I don't HAVE a Sprint iPhone 5. I have an AT&T iPhone 5. It's different, internally. I can't switch over to Sprint, even if I wanted to. I'd have to buy a whole different phone.
OHHHHH -- but looking it up, I thought mine was the CDMA type, which couldn't be used in the UK. I guess the older Sprint phones were that kind. Looks like mine is a GSM type and *could* be used in the UK. It does have a SIM slot. Thank you for making me double and triple check my facts, cuz I had them wrong!
http://www.pcmag.com/article2/0,2817,2407896,00.asp
Looks like it's time to ask AT&T to unlock my phone, and I'll get myself a SIM once I arrive over there.