Union contracts for 40,000 AT&T workers expire at midnight, leaving them free to call a strike to pressure the company at the negotiating table.
The workers are on the shrinking local-phone and long-haul data side of the business, and located mainly in the Midwest and California. Four separate contracts covering different regions are being negotiated, and the workers have authorized the Communications Workers of America to start strikes.
When the last big batch of contracts was negotiated three years ago, the parties kept talking past the contract expiration, and reached agreements without a strike.
Dallas-based AT&T is the country's largest employer of unionized workers. About 140,000 of its 256,000 employees are union members.
At issue in the negotiations are job protection clauses and health-care premiums and co-payments.