According to Apple, A1660 and A1661 cannot do LTE in most of the world. My experience suggests that many functions are unpleasantly slow or even impossible without LTE. But I haven't been able to find an A1784 or A1778 in Oregon or on the Apple website.
Contacted Apple and got an "expert" who insisted the A1661 works anywhere in the world and seemed to think that web page was inaccurate.
Online descriptions of LTE suggest that there is no hard-and-fast number to describe its bit-rate.
If I get a CDMA iPhone 7, is there a reliable description of what kinds of apps will not work in Mexico City or Toronto or Madrid or Seoul or similar places?