NEW YORK (Reuters) - AT&T Inc workers are suing the telephone operator for an estimated $1 billion in overtime payments in two class action lawsuits that say it is wrongly depriving about 5,000 employees of overtime pay.

The lawsuits say that a company-wide policy exempting first-level managers from overtime pay was a violation of federal labor laws and California state laws, according to Sanford Wittels & Heisler, the law firm filing the case.

AT&T, which employs about 290,000 people and is expected to generate $123 billion in revenue this year, declined to comment on the cases directly but said that it complies with all federal and state wage laws.

One of the cases filed in Atlanta in the United States District Court for the Northern District of Georgia says first-level managers are the lowest in a seven-tier management hierarchy at AT&T and have only minimal supervisory roles.

But for the last few years these workers from nine former BellSouth operating states have been asked to work more than the regular 40-hour week, and up to 100 extra hours in some cases, without any overtime pay, according to the case.

Steven Wittels, a partner in the firm, said that under federal and state laws workers need to have clear managerial responsibilities in order to be exempt from overtime pay.

“If you call somebody a duck and it doesn’t quack, it doesn’t swim and it doesn’t have wings, it ain’t a duck,” he said, adding that BellSouth used to pay the same workers overtime until a policy change in 2007.

His firm has already succeeded in gaining class action certification for workers in a similar suit filed in a Connecticut subsidiary of AT&T Southern New England Telephone Company, according to Wittels.

One of the lawsuits, related to employees of the former BellSouth, was filed in court in Atlanta on Wednesday and another, related to former Pacific Bell employees, was filed in San Francisco. AT&T bought BellSouth at the end of 2006 after Pacific Bell became part of AT&T in 2005.