We tested T-Mobile for a couple of months, but gave it up when we kept losing reliable signals whenever we got more than a few miles from major cities and highways. We've found Verizon serves us the best in the most places, and AT&T is running a close second. We have a Maximum Signal MaxAmp RV cell booster/repeater on board, and while it does perform miracles at times in getting usable signals for us, even that couldn't always help with T-Mobile. Our previous WeBoost 4G-M was even worse in those conditions. They can't boost what isn't there.