If you want to enable T-Mobile voice and data on your AT&T Galaxy Note, you will need to unlock SIM on your AT&T Galaxy Note SGH-i717 first.
Step 1. Dial *#06# in your Dialer.
Step 2. Write down the IMEI number you get.
Step 3. Go to Cellunlocker.net. (You can also use any other cellular unlocking service of your choice. I just used this one since it came up first on Google.)
Step 4. Choose i717 Galaxy Note 4G LTE or the phone you have. It should also work for Rogers/Telus/Bell.
Choose AT&T for carrier.
Enter your IMEI number.
Step 5. You can pay like $24.95 to unlock your phone. You should receive your unlocking code within 5-10 minutes in your e-mail.
Step 6. Reboot your phone after putting T-Mobile SIM card in (or any other SIM card that’s non-AT&T).
Step 7. When your phone reboots, it will ask you for the Network Lock Control Key. Enter the Network key you got in your e-mail and it should unlock your AT&T Galaxy S2.
Now your AT&T Galaxy S2 should be able to use T-Mobile voice and edge speeds for internet. For 3G/4G, you will have to install a T-mobile modem, which is coming next.
Q: I am still not getting any signal on T-Mobile!
A: This guide was written originally for Gingerbread. It’s most likely because you are running ICS. You can install an ICS modem instead to get it working, get it here.
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You will need a rooted Galaxy Note to install all ROM/kernels.
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