How to convert CDMA M8 (Sprint/VZW) in a GSM/Global device

Hi all, today I want to thank all the xda users with a little guide. Here I found a lot of help and I want to share my new knowledge.

Sprint and VZW M8 are CDMA devices used in the US, and based on HTC site works on these LTE bands:
EMEA: 800/900/1800/2600 MHz
Asia: 700/900/1800/2100/2600 MHz
AT&T: 700/850/AWS/1800/1900/2600 MHz
Sprint: FDD 800/1900 MHz , TDD 2600 MHz
Verizon: 700/AWS/1800/2600 MHz
TMUS: 700/AWS MHz
Is these an hardware limit? Is the VZW really made with different hardware? Some says yes, but generally I'm a donkey and I always want to try to brick my phone :laugh:

What happens when you are overseas?
You can sim unlock your device by the code supplied by US carrier, also by unlocking bootloader and installing new custom rom (GPE/cyano); but the "firmware" will restrict the bands in order to the original carrier frequencies!!!
So:
for VZW; you can call with a gsm mode but NOT use LTE with some carriers;
for Sprint: any EU sim will not be recognized at first boot! you ever going to settings and put global mode, dial *#*#4636#*#* to set GSM/LTE auto mode and AUS bands, return to settings to set LTE (very annoying issue).
for both: often GPS does not work!

SOLUTION: you can convert the CDMA device in a Global one (DO IT AT YOUR OWN RISK, Obviously)
1) First, go S-OFF
2) Unlock bootloader
3) put a non-red text firmware and install recovery in one step (choose your current modelID here http://forum.xda-developers.com/show....php?t=2710503)

fastboot oem rebootRUU
fastboot flash zip filename_NoRedText_hboot.zip
fastboot reboot-bootloader
fastboot flash recovery filename.img
fastboot reboot
4) Boot the stock rom and make a GPS fix with any GPS Toolbox (prevention), then reboot
5) Enter in recovery, BACKUP STOCK ROM so wipe all data
6) change cid and modelID in one step
fastboot oem writecid HTC__001
fastboot reboot-bootloader
then open twrp
adb devices
adb shell
su
echo -ne '\x30\x00\x50\x00\x36\x00\x42\x00\x31\x00\x30\x00\ x30\x00\x30\x00\x30' | dd of=/dev/block/mmcblk0p5 bs=1 seek=16384
exit
adb reboot bootloader
fastboot getvar mid (or getvar all) (verify 0P6B10000 for modelid)
fastboot reboot-bootloader
7) Install any custom rom you want and enjoy a full unlocked worldwide bands device!
You can also convert in a GPE one. Probably the device also accept a firmware of a different model ID but I haven't any interest to reflash it, the phone works great!
8) If GPS does not work, restore the original rom, make a fix, reboot, wipe and reinstall custom rom; if GPS works you can delete the stock backup.

Useful sources:
http://forum.xda-developers.com/show....php?t=2708581
http://forum.xda-developers.com/show....php?t=2708589

Then, I'm from Italy, please report any grammar lack.

Download from this link

New to Verizon, questions about LTE vs. CDMA

I live in Maine, and I just switched my two lines over to Verizon from US Cellular expecting better coverage. I typically used CDMA on USCC because the data speeds were faster and more reliable, and the better reception equaled better battery life. So now that we are on Verizon, they do not offer a CDMA option. I can use the hidden dialer code to switch it temporarily with my MXP, but the other line with a Note 4 cannot. So the Note 4 just drops calls like mad - why doesn't the dialer code work for that phone?

Secondly, is there a way to make these settings stick, so I don't have to keep switching back from LTE? I tried browsing on LTE this morning at work, just to see how it compared after using CDMA all day yesterday, and pictures would not load. At least not for several minutes (4-5 minutse), whereas on 3G they load in like 30 seconds. So I'm sold on CDMA, but sick of switching. Any advice would be great. Otherwise, we'll switch back to the better carrier.

Download from this link

Way to force CDMA instead of LTE?

Hi, we just switched from US Cellular to Verizon, and apparently Verizon does not allow users to select just CDMA like USCC. The Verizon network is also very weak here in Maine it appears (much to my chagrin). We have so many dropped calls and dead spots is laughable - if you were not pissed anyway. I'm wondering if the difference between carriers that supposedly share towers, is that on USCC I stayed on CDMA for the improved data speeds and stability, and because it yielded better battery life due to the 15dBm stronger signal.

I'd like to switch us to CDMA and test it, but the android hidden dialer code does not work on the Note 4, but does on my MXP. Is there a way to switch to CDMA?

Thanks in advance,
Moose

Download from this link