Striking union workers have claimed victory in their job action against Verizon, which led to a tentative settlement.

“Striking Verizon Workers Win Big Gains,” the Communication Workers of America declared Friday.

Strikers are expected to be back to work this week after the company and its unions reached an agreement in principle for a four-year contract.

About 39,000 landline and cable employees in nine Eastern states and Washington, D.C., have been on strike since mid-April, one of the largest strikes in the U.S. in recent years.

Verizon had trained other workers to step in but there were still delays in installations for Fios customers.

The CWA pointed out that the settlement represents the “first contract for retail wireless workers” and also “improves workers’ overall standard of living.”

The settlement applies to about 165 workers in six wireless stores in Brooklyn, New York, and one store in Massachusetts.

The strike started April 13 and included nearly 40,000 workers.

“CWA appreciates the persistence and dedication of Secretary Perez, Federal Mediation and Conciliation Service Director Allison Beck and their entire teams,” said CWA President Chris Shelton.

“The addition of new, middle-class jobs at Verizon is a huge win not just for striking workers, but for our communities and our country as a whole. The agreement in principle at Verizon is a victory for working families across the country and an affirmation of the power of working people. This proves that when we stand together we can raise up working families, improve our communities and protect the American middle class.”

Verizon said that it had high health care costs for its unionized workers, which have shrunk as it sold off large chunks of its wireline unit and focused on its mobile business, which was not unionized. It also wanted the union workers, just over one-fifth of its U.S. workforce, to agree to move around to different regions when needed, which the union opposed.

The union and Verizon are not giving details of the contract, so it’s not clear yet what the agreement entails for workers. As the number of organized workers shrinks, union fights in recent years have tended to be defensive, aimed at holding the line for their members rather than winning new benefits, said Jake Rosenfeld, sociology professor at Washington University, in an interview before the agreement was announced.

Verizon released a statement saying it’s pleased with the agreement, which has “meaningful changes and enhancements” that will make its wireline business more competitive.

Labor Secretary Thomas Perez said Friday that the agreement is being written and will be submitted for approval by union members, and he expects workers back on the job next week.

The workers had been working without a contract since last August.

New York-based Verizon Communications Inc. and the unions have been negotiating at the Department of Labor for the past 13 days, Perez said.