(AP) -- Striking Verizon employees may be back to work next 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.

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.

The president of the Communications Workers of America union, Chris Shelton, did say in a statement that the agreement is a "victory for working families" and that there will be new union jobs at Verizon. The International Brotherhood of Electrical Workers union did not immediately respond to a request for comment.

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.

The deal does include a first contract for Verizon wireless employees, says the CWA. It applies to about 165 workers in six wireless stores in Brooklyn, New York, and one store in Massachusetts.

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.

Verizon Communications Inc. shares rose 46 cents to $50.62. They are up 2 percent over the past year.

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This story has been corrected to show that just over one-fifth of Verizon's U.S. workforce is unionized, instead of about 30 percent.