That is a really good question. It seems like there has been conflicting info on 4G LTE phones and PPC, and with the forum search broken, I can't search. It seems like 4G LTE phones should be backwards compatible, but are they? Any definite answers would be appreciated!
My PagePlus Phone History---12 Years & Counting
*Ericsson AF738, Jul 2001-Dec 2003, *Qualcomm QCP 2760, Dec 2003-Feb 2008, *LG VX-8600, Feb 2008-Apr 2010, *Samsung Omnia SCH-i910, Apr 2010-Nov 2011, *HTC Droid Incredible (CM7.2 ROM), Nov 2011-Jun 2013, *HTC Droid Incredible 2 (CM7.2 ROM), Jun 2013-Present