FILE PHOTO: The AT&T logo is pictures on a building in Los Angeles, California, U.S. August 10, 2017. REUTERS/Mike Blake

(Reuters) - AT&T Inc said on Wednesday weakness in its wireless equipment unit could weigh on its third-quarter revenue.

Low upgrade rates are hurting its wireless equipment revenue, AT&T said.

The company also said it expects current-quarter revenue at its WarnerMedia unit to fall by $400 million from a year earlier, mainly due to a strong second half last year at Warner Bros.

AT&T forecasts premium TV subscriber trends to improve in 2020, as it expects far fewer customers on promotional pricing and the nationwide launch of AT&T TV.