[Galaxy Tab 4 Q&A, Help & Troubleshooting] deuceduck:
Bought this tablet on eBay cheap. Then realized it's Sprint. Thought about the NV edit to add band IV LTE, but could not get passed the MSL requirement. Sprint was no help. Same with the apps, save for one that I found here. The Sprint Samsung Galaxy Unlock apk sometimes after a reboot I get the Invalid SIM error. This apk solves that quickly.

My intent was to first clear the current carrier information. Such as the user name and anything relating to Sprint.

I have at my use an Octoplus box with latest software.

I threw everything I could at this Sprint tab including flashing via Octoplus the firmware for SM-T337A (AT&T). Which did not take nor brick my device.

I have the SM-T237P rooted with the detoxed firmware found on this forum.

I used Octoplus box to (likely wasn't necessary) flash the AT&T version SM-T337A.

This model (T337A) was useful to unlock my Sprint tab 4. I can't tell if it was necessary or not, but the process completed.

Then I found another model (T335) that had the option to Fix the MSL via Octoplus. This version is a Tab S model SM-T335.

I pressed the button and rebooted the phone.

To get into Diag-DM-ABD mode is required for any operation. EFS Professional can do this or there is a way into the service menu on the tablet.

On the SM-T237P make sure you have an active wifi connection. Then go to General | Activate this device | it should fail saying call customer service by pressing *2 on your phone. The three dots at the top right will allow access to the service menu. Click on PST and you will see the ##DATA## and several other menus. From here you may change anything, if you found the MSL.

Repairing the MSL via Octoplus opened up the menu to edit the MIN and MIDN which doesn't really help me at this point.

In the service menu look for the third option down | LTE Services | click on Global and restart the device.

After reboot under | About Device | Status | my regular GSM sim card is seen and the number does show up.

That particular chip is out of service, but I did achieve my goal of removing the previous sub info.

Also new is the option to select many new network modes. I will get screen shots of what I am attempting to explain.

I had read a lot and not found too much on this Sprint SM-T237P

I understand it does not have the frequencies to be used on Wind Mobile. I should find a Bell chip and see what happens.

This is the culmination of a month's work. Utilizing Google, XDA and the Octoplus box. Some things I have done may be contrary to the user manual or common thought. When testing your new device and there isn't much that others have done, you must think outside the box and not be afraid of bricking a device. This is just my experience. Following is my log from last night.

Welcome to Octoplus/Octopus Box Samsung software version 2.0.1

-----------------------------------------------------------------------------------

To connect SM-T337A phone you have to perform the following steps:

1. Disconnect USB cable from phone.

2. Go to Menu->Settings->More->About Device.

3.Tap on "Build number" 7 times to enable developer options.

4. Go to Menu->Settings->More->Developer options.

5. Turn on "USB Debugging" option.

6. Go to Calculator application. Enter "(+30012012732+" number, to get phone dial window.

7. Enter "*#0808#" number.

8. Select "DM+Modem+ADB".

9. Press Home button.

10. Go to dial window.

11. Enter "*#9090#" number.

12. Set "Diag config" to "[1]DM/DUM over HS-USB" value.

13. Restart phone.

14. Press "Read Info" in software.

Selected firmware file: T337AUCU1ANK2_T337AATT1ANK2_ATT_Android_4.4.2.oct

Please put the phone into Download Mode and connect USB cable.

To put SM-T337A into Download Mode, You have to perform the following steps:

1. Reconnect the battery.

2. Press and hold "Volume-" + "Home" + "Power ON" keys.

3. When phone turns on, press "Volume+" key.

Found phone on

Firmware write started.

Writing ABOOT section...

ABOOT section has been written successfully.

Writing SBL1 section...

SBL1 section has been written successfully.

Writing RPM section...

RPM section has been written successfully.

Writing TZ section...

TZ section has been written successfully.

Writing DBI section...

DBI section has been written successfully.

Writing APNHLOS section...

APNHLOS section has been written successfully.

Writing BOOT section...

BOOT section has been written successfully.

Writing RECOVERY section...

RECOVERY section has been written successfully.

Writing SYSTEM section...

SYSTEM section has been written successfully.

Writing PERSIST section...

PERSIST section has been written successfully.

Writing MODEM section...

MODEM section has been written successfully.

Writing CACHE section...

CACHE section has been written successfully.

Firmware writing successfully completed.

-----------------------------------------------------------------------------------

To connect SM-T355 phone you have to perform the following steps:

1. Disconnect USB cable from phone.

2. Go to Menu->Settings->More->About Device.

3.Tap on "Build number" 7 times to enable developer options.

4. Go to Menu->Settings->More->Developer options.

5. Turn on "USB Debugging" option.

6. Go to dial window.

7. Enter "*#0808#" number.

8. Select "DM+Modem+ADB".

9. Press Home button.

10. Restart phone.

11. Press "Read Info" in software.

-----------------------------------------------------------------------------------

Platform: Samsung Android

Selected port: COM31

Selected model: SM-T355

Detected phone model: SM-T237P

Firmware compiled date: Tue Dec 2 21:07:56 KST 2014

PDA version: T237PVPU1ANL1

CSC version: T237PSPT1ANL1

SW version: T237PVPU1ANL1

Phone IMEI: 99000xxxxxxxxx

Phone SN: 00000000000

Android version: 4.4.2 (KOT49H)

Checking Root:

Phone is Rooted.

Reading security backup, please wait...

Backup saved as C:\Program Files (x86)\Octoplus\Octoplus_Samsung\BACKUP\Security-SM-T355-27-07-2015_18-51-41 file

Reseting MSL...

MSL reset successfully.

Please, restart the phone to apply changes

-----------------------------------------------------------------------------------

Platform: Samsung Android

Selected port: COM31

Selected model: SM-T355

Detected phone model: SM-T237P

Firmware compiled date: Tue Dec 2 21:07:56 KST 2014

PDA version: T237PVPU1ANL1

CSC version: T237PSPT1ANL1

SW version: T237PVPU1ANL1

Phone IMEI: 99000xxxxxxxxx

Phone SN: 00000000000

Android version: 4.4.2 (KOT49H)

Checking Root:

Phone is Rooted.

Reading security backup, please wait...

Backup saved as C:\Program Files (x86)\Octoplus\Octoplus_Samsung\BACKUP\Security-SM-T355-27-07-2015_18-52-46 file

Unlocking phone...

Phone is successfully unlocked

To finish the operation, please restart the phone via phone's menu (don't disconnect the battery!)

My question to the forum: Was it the MSL Reset that flushed the Sprint subscriber info or was that the unlock or maybe just enabling LTE Global which never stuck until I did the MSL reset. Fun, fun testing.