[Galaxy S 5 Q&A, Help & Troubleshooting] botwa2000:
Hi there,

I just got and rooted a Korean version of SGS5 SM-G906K.

It doesn't by default support an LTE band B20 of 800 MHz.

Does anyone know how to enable it?

Any help is highly appreciated!

[EDIT]

After several weeks of trial and error, I decided to generalise the thread for more devices and make it more focused on a solution.

The thread will be covering QualComm SnapDragon 805 Samsung devices, in particular:

Galaxy S5 SM-G906K

Galaxy S5 SM-G906S

Galaxy S5 SM-G906L

...running on MDM9x35 Gobi discrete modem.

Topic focus - unlocking additional LTE bands.

As far as I know, additional LTE bands have been successfully unlocked on other brands however not yet on those I want to tackle.

Thanks for providing inspiration, guidance and working assumptions to following threads and folks:

http://xdaforums.com/galaxy-s5/general/how-to-add-rf-lte-frequency-bands-to-t2886059

http://xdaforums.com/crossdevice-dev/sony/thread-progress-please-leave-im-updating-t2871269

[MENTION=5353566]fffft[/MENTION]

[MENTION=4300205]olokos[/MENTION]

[MENTION=5733862]BlackSoulxxx[/MENTION]

[MENTION=336579]Isriam[/MENTION]

[MENTION=5971873]dl12345[/MENTION]

Attempts have been made to edit various NV values (e.g. 01877, 06828, 06829) using EFS Professional or QXDM / QPST software.

Although some folks succeeded to make the new edits stick after phone reboot, the procedure did not result in enabling those LTE bands as of yet.

Guide into editing NV values that worked for me:

1. My phone:

SM-G906K running stock rooted.

2. Entered into diag mode from *#0808# dial pad command:

AP

RMDIS + DM + MODEM

I know that recommended mode is CP but my phone wouldn't connect like that.

3. Entered into USB debug mode,

4. In Terminal Emulator ran

su

setenforce 0

5. Connected to PC running Win8.

6. In device manager enabled hidden devices, then got my Sammy in ports COM15 & COM16.

None of them showed diag but COM16 was later recognised by NV editor.

7. I used QPST v2.7 Build 4.11 and QXDM-3.12.714.

8. Existing LTE values: 1/3/5/7/8/17.

I ran QPST, connected port 15 - it wasn't recongnised by QXDM.

I then I connected port 16, it was recognised.

9. In QXDM changed values in NV 6828 and 6829

The values stuck after reboot.

Another important aspect of controlling the phone network behaviour is through the hidden menu.

Use with extreme care & do this at your own risk

Open the dial pad

Type: *#0011# to enter Service Mode (Be very careful with what you do here)

Note: You need to be rooted for this to work

Once in Service Mode, do the following:

Tap the menu button and tap Back

Tap the menu button again and select "Key Input" and enter an upper case Q and press OK

Tap the menu button again and select "Key Input" and enter 4 zeroes (0000) and press OK

Wait from 5 to 15 seconds. You'll see the Main Menu

Choose option [2]: UE SETTING & INFO

Choose option [1]: SETTING

Choose option [1]: PROTOCOL

Choose option [2]: NAS

Choose option [1]: NETWORK CONTROL

Choose option [4]: BAND SELECTION

Choose option [4]: LTE Band Preference

Choose option [7]: LTE ALL (Or you can choose any band instead)

If you want to go back then tap the menu button and choose Back (Don't press the back key)

Press the back key to exit