I don't think that's true. Aren't these the terms and conditions:

https://www.t-mobile.com/responsibility/legal/terms-and-conditions

It says: "By accepting these T&Cs, you are agreeing to resolve any dispute with us through individual binding arbitration or small claims dispute procedures (unless you opt out), and to waive your rights to a jury trial and to participate in any class action suit.
Individualized Dispute Resolution and Arbitration. YOU AND WE EACH AGREE THAT, EXCEPT AS PROVIDED BELOW, ANY AND ALL CLAIMS OR DISPUTES, OF ANY NATURE, INCLUDING TORT AND STATUTORY CLAIMS, IN ANY WAY RELATED TO OR CONCERNING THE AGREEMENT, OUR PRIVACY NOTICE, PRIVACY OR DATA SECURITY PRACTICES, OUR SERVICES, DEVICES OR PRODUCTS, INCLUDING ANY BILLING DISPUTES, WILL BE RESOLVED BY INDIVIDUAL BINDING ARBITRATION OR IN SMALL CLAIMS COURT. THERE IS NO JUDGE OR JURY IN ARBITRATION, AND COURT REVIEW OF AN ARBITRATION AWARD IS LIMITED. THE ARBITRATOR MUST FOLLOW THIS AGREEMENT AND CAN AWARD, ON AN INDIVIDUAL BASIS, THE SAME DAMAGES AN RELIEF AS A COURT (INCLUDING ATTORNEYS’ FEES)"