[AT&T Samsung Galaxy Note I717] tomin.fhl:
SOLUTION (At least one solution that works)

Ok. I have successfully managed to get T-mobile 4G working on an AT&T Galaxy Note with absolutely no freezing. I have been able to replicate T-mobile 4G with three different modems: (1) T-mobile SGH-T989 KID, (2) T-mobile SGH-T989 VKL1, and (3) Telus KJ3. These modems can be found in this post http://xdaforums.com/showthread.php?t=1507825. Also, there is full phone functionality.

Here is how I achieved T-Mobile 4G on an AT&T Galaxy Note.

PRELIMINARY NOTES

The AT&T Note was networked unlocked

I have been on T-Mobile for the past 3 years

I am on the T-mobile post paid 5GB Data Android Plan (with unlimited talk and text)

T-mobile sim was in the device while testing the solution

The Galaxy Note was rooted, and running the latest Saurom Projekt Team Rom with the kernel that comes with that rom (DA_G's kernel I think).

The phone functions perfectly. My family called while I was testing and there were no issues.

CAVEATS

Signal strength on my note was less than it was on my GS II. Indoors, I struggled to get two bars of reception.

I have yet to break 5Mbps download speeds and upload speeds are low, usually 1 Mbps or less.

HOW THIS SOLUTION DIFFERS FROM OTHER ATTEMPTS

All other attempts I have seen in both threads attempt to flash both the modem (mdm.bin) and the software that runs/communicates with the modem (amss.bin). CWM solutions were worse because those solutions also flashed two lib files (libril.so and libril-qc-qmi-1.so) that might be adding to the conflict.

Since all of the other solutions were resulting in lags/freezes/crashes, it seemed that either mdm.bin, amss.bin, or one of the lib files must be conflicting with some other component on the device. Since it was confirmed that 4G was possible before the lags/freezes/crashes, it seemed that the modem file was compatible. The only solution left was to eliminate any conflict possibly arising from the amss.bin or the lib files. In a nutshell, the solution is to flash mdm.bin without amss.bin or the lib files.

THE SOLUTION

I recommend using SOLUTION 1 below. It is easy and all you have to do is download the modem you are interested in and flash through CWM. But if you are game, you can go for SOLUTION 2 which is a bit more technical and requires comfort with adb and the dd command. That solution relies on adb and dd to write the mdm.bin file directly to the mmcblk0p17 partition on the device. Before we do that you MUST (1) have a NANDdroid back up and (2) you must follow the instructions here to backup your current mdm.bin/mmcblk0p17 partition so you can restore it when you need to.

- NANDROID and OTHER PREP

1. Do your nandroid backup (sorry, I can't explain that here)

2. Power off phone, remove battery, and install T-Mobile sim with a smartphone/data plan.

3. Power on phone

4. Make sure you have adb working on your pc with all the necessary samsung usb drivers etc. (sorry, I can't explain that here)

5. Make sure usb debugging mode is on (Settings, Applications, Development)

6. Make sure "Unknown sources" is on (Settings, Applications ... this may not be necessary, but it worked for me, so let's just do it.)

- SOLUTION 1 - THE NICE AND EASY WAY

1. Using CMW, flash your modem of choice from the following:

- Telus Kj3 - http://www.mediafire.com/?y53w18h8xx76u7z

- T-mobile SGH-T989 KID - http://www.mediafire.com/?o7d1z5xlox1jxkp

- T-mobile SGH-T989 VKL1 - http://www.mediafire.com/?872a6s8mccw4dxu

2. Reboot your phone.

3. That's it. You should be ready to roll and can ignore all the technical stuff below. That is just there so people can build on the work.

- SOLUTION 2 - THE TECHNICAL WAY (or if you have trouble flashing the above)

1. Create three folders on your internal sdcard (/sdcard) or your external sd card (/sdcard/external_sd). These folders are (1) ATT, (2) TMOBILE, and (3) TELUS. Then create two subfolders in the TMOBILE folder: (a) KID, and (b) VKL1.

2. Backup your original mdm.bin and amss.bin partitions

- Get adb up an running and make certain your phone is connected to your pc.

- Run the following commands to back up your mdm.bin. You may as well back up your amss.bin as well for good measure.

- For those using the internal storage use the following commands.

adb shell dd if=/dev/block/mmcblk0p17 of=/sdcard/ATT/mdm.bin

adb shell dd if=/dev/block/mmcblk0p13 of=/sdcard/ATT/amss.bin

- For those using the external sd card use the following commands.

adb shell dd if=/dev/block/mmcblk0p17 of=/sdcard/external_sd/ATT/mdm.bin

adb shell dd if=/dev/block/mmcblk0p13 of=/sdcard/external_sd/ATT/amss.bin

- Good. Now your original modem files are backed up on your internal storage or external sd card. Please don't overwrite them. Back them up somewhere else just to be safe.

3. Now we need to download and store either one of the T-Mobile mdm.bin files or the Telus mdm.bin file.

- Download the modem you want to test from this post http://xdaforums.com/showthread.php?t=1507825.

- I had the best results with the T-mobile SGH-T989 KID so I'll use that for these instructions.

- After downloading the modem, extract the mdm.bin file. Remember, this is the only file you want to mess with right now. (Maybe when we do more tweaking we can optimize the amss.bin file and the lib files as well.)

- If you downloaded the T-mobile SGH-T989 KID, save the mdm.bin file in /sdcard/TMOBILE/KID folder (internal sd) or the /sdcard/external_sd/TMOBILE/KID (external sd card).

- if you downloaded the T-mobile SGH-T989 VKL1, save the mdm.bin file in /sdcard/TMOBILE/VKL1 folder (internal sd) or the /sdcard/external_sd/TMOBILE/VKL1 (external sd card).

- if you downloaded the Telus KJ3, save the mdm.bin file in /sdcard/TELUS/ folder (internal sd) or the /sdcard/external_sd/TELUS/ (external sd card).

- Good. Now you have the mdm.bin file in a location that tells you exactly which modem you will be flashing.

4. Now all we need to do is copy the mdm.bin to the correct partition on the Note.

- For those using the T-mobile SGH-T989 KID modem the use the following command without the quotes.

"adb shell dd if=/sdcard/external_sd/TMOBILE/KID/mdm.bin of=/dev/block/mmcblk0p17" (external storage)

"adb shell dd if=/sdcard/TMOBILE/KID/mdm.bin of=/dev/block/mmcblk0p17" (internal storage)

- For those using the T-mobile SGH-T989 VKL1 modem use the following command without the quotes.

"adb shell dd if=/sdcard/external_sd/TMOBILE/VKL1/mdm.bin of=/dev/block/mmcblk0p17" (external storage)

"adb shell dd if=/sdcard/TMOBILE/VKL1/mdm.bin of=/dev/block/mmcblk0p17" (internal storage)

- For those using the Telus KJ3 modem use the following command without the quotes.

"adb shell dd if=/sdcard/external_sd/TELUS/mdm.bin of=/dev/block/mmcblk0p17" (external storage)

"adb shell dd if=/sdcard/TELUS/mdm.bin of=/dev/block/mmcblk0p17" (internal storage)

5. If all of that went well, all we have to do now is reboot, let the device settle down (updating the storage takes a little while longer since we put all those modem files in there), and then force the device to use HSDPA.

- Enter the following command without quotes

"adb shell reboot"

- Let the device restart

- Let media scanning complete (really, be a little patient with it)

- Look for the 4G icon to appear where only an edge symbol used to be.

- If there is no 4G icon, check you reception strength. I had low reception indoors that improved when I went outdoors.

- If after trying to get a stronger signal you still only get edge, you might need to force your phone to use HSPA only.

6. Forcing your phone to use HSPA

- Go to Settings

- Go to Wireless and network

- Scroll down and go to Mobile networks

- Go to Network mode

- Select HSPA only

OR

- Enter *#2263# on the dialpad

- Select [2] WCDMA Band Preference

- Select [3] WCDMA 1700

7. Ok, that's it. Next step, reading through your posts and collecting my bounty :D.

Enjoy the picture evidence of my T-mobile on the AT&T Galaxy Note with no lag/freeze/ or crashes.