The GTE Corp. subsidiary, one of the nation's largest long-distance telephone companies, was sued for allegedly overcharging its customers millions of dollars on calls made during Thanksgiving and Christmas. The class-action suit was filed in Los Angeles Superior Court by the Los Angeles-based Center for Law in the Public Interest. A complaint was also sent to the state Public Utilities Commission. The suit alleges that the company charged regular daytime rates from 8 a.m. to 5 p.m. on Nov. 22 and Dec. 25 instead of the lower evening rates that it advertised. The group estimated the overcharges at $2 million to $4 million. Sprint has 2 million to 3 million customers.