T-Mobile USA Inc. is planning to move to arbitrate claims filed over last year’s data breach, setting the stage for a potential fight at the start of the litigation.

At the first hearing in the multidistrict litigation, T-Mobile attorney Kristy Brown on Tuesday would not give specifics about how many of the 50 million potential class members could be subject to an arbitration clause. She said that number was premature until attorneys filed their master complaint with named plaintiffs.