I performed the permanent SIM unlock as described in another thread. I was successful in unlocking my phone not only for international GSM service but also domestic GSM service. I have an active AT&T prepay SIM and can use the Sprint LS980 phone on AT&T in the states all day long, make and receive phone calls on that number, send texts and even have HSPA+ data.
However, in while performing this hack, it requires editing a build.prop string. I went as far to do the hack on a custom ROM which I lost the ability of using 5689#*980# to access the IOT menu that was crippled in the ZVC update. Guess what, when a certain build.prop entry is changed which tells the handset what carrier it identifies with, the items in the IOT menu change. In custom ROM's the IOT menu is accessed with 277634#*#. With the build.prop identified as OPEN instead of SPR (sprint), a lot of options presented including the ability to select LTE bands. So I learned that the items that show in the IOT menu are somehow enabled based on the RO.TARGET.OPERATOR string. In the case of being set to OPEN, I could select band 1, 2, 3, 4, 5, 7, 8, 17, 20 or 40. No band 25, 26 or 41 but I have inclination that if the right conditions were set that those bands would present.
Anyone that's in to the inner workings of Android, want to take a crack at getting access to the old IOT settings from within the ZVC/KK ROMs?