Parents and teachers who are fed up with the Bloomberg administration’s ban on cell phones in city schools are planning to protest outside a Brooklyn school this morning.

The president of the United Federation of Teachers, Randi Weingarten, said cell phones are a “lifeline” for parents and that students should be allowed to carry them to school as long as they are shut off during the day. She will join Council Member Bill de Blasio outside M.S. 51 in Park Slope to call for the Department of Education to amend its policy.

The ban has been on the books for almost two decades, but until now many schools have operated under a “don’t ask don’t tell” policy. Last month, the issue came to a head when Mayor Bloomberg introduced new random metal detector searches at the city’s middle and high schools. Intended to remove weapons from the classroom, safety officers started confiscating contraband cell phones, iPods, and CD players as well. Many parents didn’t become aware of the policy until letters went home about the new random searches.

Parent groups have been complaining that their children need cell phones to safely travel around the city and coordinate hectic schedules. Some parents have accused the mayor of being “out of touch.”

Mr. Bloomberg and the schools chancellor, Joel Klein, have been firm in saying that cell phones don’t belong in the schools even if they remain tucked away in lockers or school bags. Mr. Bloomberg said teachers don’t need the added task of having to monitor if their students are text messaging under their desks or using their phones to cheat on tests.

The UFT’s executive committee passed a resolution last week urging the education department to allow students to bring cell phones to school but prohibit their use while there. The resolution also called for increased penalties for students who violate the rule.