Default can i somehow use a custom rom to gain hspda+ on h2o 4.2.1 i535

well im going thru alot of postings im certain my answer is no but just in case i may have missed somthing its been awhile since i had a s3

got my hands on this s3 4.2.1 did casual and just using it on h2o with a mini sim got e

but thats boring

will upgrading it to 4.3 enable anything

like on my verizon s4 upgrading to 4.3 enabled lte for my old tmobile sim but yeah i know thats diff bands altogether
but i went to h2o so as to be able to use my iphone too without unlocking it

so im just screwing around poping my simcar din and out of all these devices
im happy with hspda on the s4 and 4g on iphone

but using this s3 is almost archaic to me now with edge 2


im wondering if either changing recovery loading a rom and or kernel radio combo woul dyeild anything interesting or just waste my time

for refrence
h2o is att mvno

ill keep looking in the meantime

i also had a really odd issue with another s4 verizon where h2o failed to even register on 4.2 i never did figure out what was wrong i even went as far as upgrading it to 4.3 it acted like it was blocked out in the end the only way to get it to even register service was to root enter service menu and set the band myself global mode seemed to aquire signal then bump off network or get network but couldnt place a call i never did figure out what was wrong with that dumb handset

i wonder if forcing this handset onto a certain band would do anything or acquisition order or am i missing the band alltogether
ill keep poking around

this is also my first galaxy handset with screenburn how wonderfull looks like ghosted dialer screen ..


i535vrbmf1
build jz054k.i535vrbmf1
4.2.1