Can a no contract AT&T Lumia 640 after unlocking, work with T-Mobile are the bands for 4g good?

[Windows Central Question]

is no contract att lumia 640 after unlocking can work with tmobile are the bands for 4g good

i wantted to but the att 640 which is in offer but im a tmobile user ... i have a doubt about 4g band frequency of att and tmobile and wanna make sure before i buy

 

[libra89]

Re: is no contract att lumia 640 after unlocking can work with tmobile are the bands for 4g good

Someone tested this with that very same phone, and said that it is fine. Check out this post: http://forums.windowscentral.com/microsoft-lumia-640/395988-3.htm#post3316705

The same person also makes a follow up post about it with a picture showing proof.