I'm a t-mobile customer here in New York City, I bought 3 blackview phones for my family waited almost three months to get the phones. Long story/ short they don't work in the United States with t-mobile. not only on 4g but also 2g. So basically I have 3 expensive paper weight's that I waited months to get.
I did read the specs and contacted t-moble before buying them the agent I spoken to said the bands are within there network and should work. The only thing that worked some of the time was text. Could not receive or make calls without it dropping in seconds and no data connection at all.