The IBEW is one of the unions that represents AT&T workers.
AT&T, which employs a total workforce of 256,000, said the pact extends all terms of a current contract without modification until June 22, 2013.
Most employees covered under the contract are based in Illinois and northwestern Indiana; the other workers are spread out across the country, AT&T said.
AT&T hasn't always been able to make the peace with its union-represented workers. In April, contracts covering 40,000 workers expired, and thousands of workers in California and Nevada walked off the job for a day last month in the midst of contract negotiations between the telecom titan and the Communications Workers of America.
Dallas-based AT&T and the workers continue to bicker over such matters as healthcare, pensions, wages and overtime. However, Seth Rosen of the CWA's District 4 representing workers in the Midwest said progress had been made on a number of issues, including attendance, employment security and overtime.