About 21,000 AT&T (T) - Get AT&T Inc. Report workers could begin striking as soon as Monday, CNNMoney reports.

The Communications Workers of America (CWA) members have been working with the telecommunications firm on an extension of their previous labor contract since early February. 

The union gave AT&T 72-hours notice today of a possible walk out.

"We have given AT&T every opportunity to show their commitment to finding common ground and a fair contract," VP of CWA District 1, Dennis Trainor said. "Time is running out for AT&T to stop undermining good jobs, quality customer service and its long-term success. The pieces are all in place now, and we'll strike if necessary."

TheStreet Recommends

"We continue to bargain with the union and remain confident a fair agreement can be reached," AT&T responded. "The contract covers good paying U.S. jobs averaging nearly $70,000 a year in pay and benefits."

Shares of AT&T closed lower nearly 1% on Friday. 

(AT&T stock is held in the Dividend Stock Advisor portfolio. See all of the holdings with a free trial.)

(What will move markets this quarter and how should investors position themselves ahead of time? Jim Cramer sat down with four of TheStreet's top columnists recently to get their views. Click hereto listen to his latest Trading Strategies roundtable with them and read their advice for stocks, bonds, forex and gold.)

Editors' pick: Originally published April 28.