Cant speak for everyone else, but for me:
1. For my first phone on 4.4 LTE was on the screen and active (blue colored) and your LTE data will work and have LTE speed, but when you try and make a phone call, send a text/receive a text or any other general phone function it will fail, unless you manually in the settings shut off LTE. When your done with the call or the text, etc youll have to turn LTE back on to have LTE.
You must change the settings as this thread describes http://forum.xda-developers.com/show....php?t=2591954
This will allow you to run HSPA+ until they release an update which will fix the LTE glitch for other 1700 bands. Not sure when this will be since, they are still working on the update to 4.4 for those who werent lucky enough to receive the update, or unlucky enough for the update to harm they're phone.
2. On 4.2 I put in my sim, showed LTE active (blue colored), I tried to use data but it said "no internet connection", when i tried a phone call it had no problems switching from LTE to the lower band then back to LTE, but for some reason LTE just didnt work for me.
I just retried all the settings in the thread I just linked, and had the same result as 4.4 with no problems as of yet.
If I get a little more time between studying and work this weekend Ill retry 4.2.2 LTE without any changes since I just read something between one of the 6 threads about this I am monitoring, which reported someone on 4.2.2 had an issue with shutting off WIFI and it taking an hour to get LTE data to work every time he/she switched from wifi to cell data. I cant remember if I had wifi on when I first put in the sim, I was just concentrated on getting my phone back to normal operation and reinstalling and completely re doing everything I did 4 days before.
4.2 Users: If the correct APN info is loaded you will receive LTE and HSPA+ coverage (in refarmed areas which is most areas now if you're not rural). Device will switch to HSPA+ when making a call then bounce back to LTE when the call is complete. This is because carriers are not yet sending voice call over LTE. The phone is completely usable like this.
4.4 Users: LTE service will cause phone calls and sms failures. The device will throw a roaming error and kill the call immediately. The fix is to put the phone into UMTS mode only and use it without LTE for the time being unless you want to manually Toggle back and forth all the time.
Details can be found in my thread here: http://forum.xda-developers.com/show....php?t=2591954
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