SAN FRANCISCO — A suit against AT&T claiming hundreds of “field managers” were cheated out of overtime pay has cleared a hurdle for gaining class action status and is on the fast track to trial, the plaintiffs’ firm says.

Last year, Sanford Wittels & Heisler filed a pair of actions in San Francisco and Atlanta seeking combined damages of $1 billion. The firm also is behind a third pending suit in Connecticut.

The suits claim the telecommunications company improperly classified hundreds of employees as “field managers” to avoid paying them overtime despite 50-, 60- or even 70-hour weeks.

San Francisco federal Judge Charles Breyer on Nov. 19 granted a motion for conditional collective action certification and has given the parties seven months to complete class and merits discovery.

Breyer is allowing potential class members 60 days from the time they are notified to opt-in to the suit. Sanford Wittels says there are more than 1,300 AT&T employees in the state who are or were employed at either company since December 2005 who may be eligible to join the suit.

“Our Connecticut class action against AT&T’s subsidiary SNET is being teed up for trial in May 2010, and now our California case is on the same fast track for trial,” Jeremy Heisler, a partner in the firm’s New York office, said in a prepared statement.

AT&T is represented by Paul, Hastings, Janofsky & Walker. Lawyers at the firm’s San Francisco office did not immediately respond to inquiries.