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 One of the suspensions was later rescinded.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 or not the train or bus is in motion. Drivers are also barred from using hands-free cellphone devices.
"The MBTA will continue to enforce the policy and discipline those who violate it," said Joe Pesaturo, MBTA spokesman. "The MBTA takes this matter very seriously."
Pesaturo also pointed out that the drivers disciplined were a fraction of the 2,200 employed by the transit authority. MBTA bus drivers alone made more than 101 million trips during the last fiscal year, he noted.
MBTA officials say they rely in large part on riders to report any actions of MBTA drivers that they think could be potentially dangerous, including cellphone use.
In just the past 14 months, the T has received 242 complaints about cellphone use by bus drivers, subway operators, Silver Line drivers, and commuter rail operators.
A call to the union representing MBTA drivers was not immediately returned yesterday.
MBTA General Manager Daniel Grabauskas has taken steps to discourage the use of cellphones by drivers.
Those steps include the creation of an agency "hot line" that relatives and friends of T drivers can call in an emergency when they need to contact a driver instead of trying to call them on their personal cellphone.
Besides the use of a cellphone, the agency also bars operators from reading books or magazines, playing the radio, eating, watching portable televisions, or listening to iPods or MP3, CD, or cassette players while on the job.
The focus on cellphone use by MBTA drivers was prompted by last month's fatal trolley accident.
Operator Ter'rese Edmonds, 24, of Boston was killed when her trolley slammed into a slower-moving trolley just outside Woodlands Station in Newton during the evening commute.
Investigators looking into the crash initially focused on reports from passengers that Edmonds had appeared to be using a cellphone before the accident.
That theory has since been debunked by Middlesex District Attorney Gerry Leone, who released a report earlier this month that concluded Edmonds wasn't talking on her cellphone or sending text messages or e-mails in the moments before the accident.
Leone said there was also no evidence that Edmonds was in the process of using the Internet on her cellphone before the crash.
About a dozen passengers were hurt in the May 28 collision.
The early speculation that Edmonds might have been on her phone prompted Grabauskas to renew a warning to T operators to put down their cellphones.
