Sprint phone
I think scaredpoet is right on all counts. We just bought a Sprint iPhone 6 to send back to China. We believe it will work on both China Unicom and China Mobile, which are CDMA and GSM networks respectively. We think this because - I think - all the phone are basically multi-band/multi-protocol wrt the cell network.
We bought the Sprint model A1586 because Sprint and China use a similar LTE network (TDD, 2500 MHz and Band 41). Presumably, Sprint phones are locked in the U.S. but unlocked internationally. Can't confirm that, however.
We were in a T-Mobile store a few days ago and were told by an employee (perhaps incorrectly) that, if we buy a full-price, no contract T-Mobile model, we must buy 1 month of pay-as-you-go and after a few weeks call T-Mobile and they will give us an unlock code.
GF's China Unicom CDMA iPhone 4 works fine using a T-Mobile SIM here; an unlocked ATT iPhone 5s is working well using a China Unicom CDMA SIM in China. Her iphone 4 with the China unicom SIM in it connected to ATT here (showing that even the 4 is operationally multi-radio, both GSM and CDMA).
Didn't think to try the iPhone 6 here on an activated T-Mobile SIM. SP is correct that Sprint will not connect your phone to their network unless it is a Sprint phone - but an already activated Sprint SIM will connect a compliant phone.
I'm posting here because we did most of our research at macrumors.com. If things go awry or I have new info to report I will post it somewhere here at macrumors.
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Sprint offers a third version A1586 (6) and A1524 (6+). This model has only been available via Sprint and is ALWAYS sold locked. This model supports GSM, LTE and CDMA but also supports TD-LTE and TD-SCDMA. "You can get access to TD-LTE and TD-SCDMA bands which opens up use to basically every carrier in the world, this will prove to be especially useful in China." This phone is the most versatile and previously was only available in a locked version.
I'm assuming that Apple will be selling the A1586/A1524 versions as the "SIM-Free" version. Unlocked and compatible with almost every carrier in the world.
Lots of articles out there about this. I found this
one to be the clearest.
Thanks, jadallahyk. We just bought the Sprint A1586 and it went to China yesterday. Did not even take it out of the box. So, I can't comment about removing SIMS, etc. Maybe I will know more later.