Dozens of MBTA bus drivers and subway operators have been disciplined for using cell phones while on the job during the past two and a half years.

Records obtained by The Associated Press show that penalties for the Massachusetts Bay Transportation Authority drivers ranged from a day suspension to, in at least one case, the firing of a subway operator.

Use of a cell phone by drivers is considered a safety violation and is strictly prohibited by MBTA employee rules. It can lead to suspension and dismissal in the case of repeated violations.

At least 44 individual drivers have been cited by T officials since January, 2006. About three-quarters of the disciplinary actions involved bus drivers. One of the suspensions was later rescinded.

Drivers can be cited whether the train or bus is in motion or the cell phone is actively being used. Drivers are also barred from using hands-free cell phone devices.

"The MBTA will continue to enforce the policy, and discipline those who violate it," said MBTA spokesman Joe Pesaturo. "The MBTA takes this matter very seriously."