AT&T Inc. on Thursday posted a 2.5% rise in revenue for its core phone and Internet business in the first quarter, as the telecom giant benefited from the expansion of its fiber internet and 5G services.

The Dallas, Texas-based firm — whose WarnerMedia unit completed its merger with Discovery Inc. earlier this month to form the new media firm Warner Bros. Discovery —  added 691,000 monthly phone subscribers during the quarter.

AT&T is returning to its roots of providing wireless services after unwinding a years-long effort to become a media and entertainment company.

Shares of AT&T rose 1.5% to $19.73 in premarket trading.

The company's revenue for the standalone AT&T excluding WarnerMedia rose to $29.7 billion in the first quarter from $29 billion a year earlier.

Total revenue, however, was down more than 13%, reflecting the impact of its divested satellite TV business and weakness in its business wireline unit.

The company added 289,000 fiber internet customers during the quarter ended March 31.

Total global subscribers for premium TV channel HBO and streaming service HBO Max, which are part of WarnerMedia, rose by 3 million from the previous quarter.

Net income attributable to common stock fell to $4.8 billion, or 65 cents per share, from $7.5 billion, or $1.02 per share a year earlier.