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 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…