SAN FRANCISCO—A federal judge said he’s ready to bless an unusual $40 million deal that TracFone Wireless Inc. reached to settle lawsuits brought by private plaintiffs and the Federal Trade Commission.

On Thursday U.S. District Judge Edward Chen of the Northern District of California said he plans to give preliminary approval to the settlement, which resolves claims the nation’s largest prepaid cellphone service provider reduced data speeds for some customers with unlimited plans. Chen scheduled a fairness hearing on the class action settlement for June 23.