AT&T Inc. agreed to buy the consumer fiber operations of Lumen Technologies Inc. for $5.75 billion, expanding its fast broadband service in major cities like Denver and Las Vegas.

AT&T has clinched a deal to acquire Lumen Technologies' consumer fiber operations for $5.75 billion in cash, the companies said on Wednesday, as the wireless provider adds further scale to its national fiber footprint.

AT&T has agreed to acquire substantially all of Lumen’s residential fiber broadband network for about $5.75 billion in an all-cash deal. Lumen’s Mass Markets fiber business includes about one million fiber customers,