It was mentioned by FCC and now stands confirmed that AT&T bound Lumia 1520 (RM-940) has no inbuilt wireless charging and only with help of wireless charging shell only.
Also, next big hint is confirmation at Nokia developer page that RM-938 is US variant and we already know that this variant has inbuilt wireless charging.
Also, RM-937 is indeed global variant (as reported by us earlier) and RM-939 is China Unicom variant, as we can see in the above screenshot. So, that leaves us with RM-938 and it is coming to US with T-Mobile bands WCDMA 1700-2100, LTE band 4 (1700/2100).
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