AT&T and T-Mobile don’t get along but it appears that the root method does. A root method has been developed for the AT&T Galaxy S7 and it’s said that the root method also works with the T-Mobile Galaxy S7. The process can be a bit daunting for someone who has never tinkered with their Android device at this level so if you’re not sure about rooting it would be best to exercise caution.
Since carrier models come with locked bootloaders it’s particularly hard to root them but it’s not like the developer community is not able to find a way around the restrictions. That’s something it happens to be quite good at.
An XDA Developers forum user has shared an AT&T Galaxy S7 root method which requires downloading engineering boot images for the device, a patched version of Odin 3, and a specific version of SuperSu.
This root method is claimed to work with both Galaxy S7 and Galaxy S7 Edge on AT&T and some say that they have successfully rooted their T-Mobile Galaxy S7 and Galaxy S7 Edge using this method.
If you do decide to try this out bear in mind that Samsung Pay won’t work if you root the device, those who have followed the procedure do say that it doesn’t trip Samsung Knox security suite.
As always, exercise caution with rooting, because only you will be responsible if something goes awry during the process.