Not sure if T-mobile follows the same procedure but I find the original solution here for S3 Frontier (AT&T). It apparently works for S2 also. I have no idea why AT&T does not release this and claims they cannot unlock wearables (in 2016).
Here is a log of the procedure, verified by both XDA folks and me.
First, you need to get the unlock code (from here at AT&T). If you are not the account holder, ask them to follow the procedure for you. To get the unlock code, you need to find out your smartwatch's IMEI number at
Settings > Gear Info > About Device. For me, the request takes about 2 business days. Some people did not get it in couple days and pinged at the customer service and went it through.
Anyway, suppose you have the 8-digit unlock code now. You get it from the email asking you to follow the procedure by first "power off the device and remove the SIM card". Yea, you can never do that for Gear S2/S3 because they use eSIM.
slapshot2286, we can unlock the device by doing the following.
- Go to
Settings > Gear Info > About Deviceand scroll down to
Software Version5 times and a keyboard will show up
#7465625*638*#and another dialog shows up, which says "Personalisation" followed by "Enter NCK"
- Enter the unlock code you get from AT&T and tap
You will then see
SUCCESS indicating you have unlocked your Gear S2/S3. Period.