An estimated 17,000 union members had gone on strike early Wednesday over a grievance about increased responsibilities for technicians who typically install and maintain the company's U-verse television system.
The spat highlighted ongoing tensions between AT&T Inc. and members of the Communications Workers of America, District 9, who have been working without a contract since April 2016.
The union announced the settlement agreement on its Facebook page late Wednesday. An AT&T spokesman confirmed that the strike "has been resolved" and that employees returned to work on Thursday.
Union officials said the walkout was triggered by AT&T's demand that technicians who typically install and maintain the company's U-Verse TV service also work on the cables and hardware for landline phone service. (AT&T's wireless division was not affected.)
"The company will no longer require technicians to perform work assignments outside of their expertise and classification," the union said in a statement.
The strike included only landline workers who belong to the CWA in California and Nevada.
Union workers have said they have been increasingly asked to perform the duties of higher-paid employees and that AT&T has proposed reducing sick leave and disability benefits and wants them to pay more for their healthcare.
AT&T has been under pressure to reduce costs as the phone market matures. Its wireless service faces increased competition from Verizon, Sprint and T-Mobile, and fewer people have been opting for landline phones.
Last month, a bargaining agreement covering some 21,000 AT&T wireless phone workers nationwide expired. AT&T would like to reach a new accord with those employees as well as the "wireline" workers — that is, workers who deal with non-wireless services such as landline phone, broadband Internet and U-verse TV — in California and Nevada.
"We're currently negotiating with the union in a good-faith effort to reach a fair labor agreement covering wireline employees," AT&T spokesman Marty Richter said in an email Wednesday. "We're the country's largest employer of full-time union labor, and our goal in these negotiations is to continue to provide our employees with high-quality union careers with wages and benefits that are among the best in the country."
12:50 p.m.: This article was updated with details of the agreement, with comments from union officials and an AT&T spokesman, and with additional background information.