Updated — Students will soon be allowed to bring their cell phones to school, reversing a longtime policy that’s grown increasingly unpopular among parents, students, and even some teachers.

Bill de Blasio is set to announce the policy change on Wednesday, which would allow principals to come up with their own rules for how cell phones can be used on school grounds. Students will still be expected to store their phones in backpacks or out of sight during most of the day, but they will be allowed to use them during lunch and in class if related to a lesson, unless principals decide otherwise, as first reported by the New York Daily News.

Lifting the ban will fulfill one of Mayor Bill de Blasio’s campaign promises. Invoking his role as a public school parent, de Blasio often spoke about how his own son, Dante, brings a phone to his high school, Brooklyn Technical High School. It would also eliminate one of the school system’s symbolic divides — between students who can bring their phones to school and those who can’t — since the ban has been enforced most seriously at schools with metal detectors, which tend to serve higher numbers of minority and low-income students.

The ban is likely to garner widespread support from parents, who have called it a safety concern since as far back as the September 11 attacks, when in the aftermath many students were unable to get in contact with their parents. Still, it will introduce new issues for educators, who say cell phones can be used to cheat, become distractions and add to classroom-management headaches.

Cell phones, beepers and other “communication devices” have been banned from schools since 1988, although students with medical reasons are allowed an exemption. Under the current policy, students caught with a cell phone are required to “immediately contact” a student’s parents and have them arrange to pick it up in person.

Still, many schools rarely enforced the ban. That leniency made headlines in 2012 after students at Stuyvesant High School freely texted one another the answers to tests they were taking. The scandal led to the principal’s removal and resulted in a crackdown on cell phones the next year.

Where the ban is enforced, students who want to have their phones nearby or play Candy Crush during their commutes have had to either circumvent the rules (by sneaking in through a back door, among other tactics) or store them off school grounds, usually for $1 a day at a nearby bodega or storage trucks that sprouted up near schools. Those costs added up, often for students whose families could least afford them, and some schools developed their own, cheaper work-arounds.

Calls to lift or relax the ban grew heavier in the last decade as cell phone ownership skyrocketed. Former Mayor Michael Bloomberg, however, refused to ease the policy, even as parents waged — and lost — a lawsuit against the Department of Education, arguing that they should be able to reach their children by phone when necessary.

Former Chancellor Joel Klein briefly eased the ban in 2008 to pilot an incentives program that rewarded students for good behavior, completing their homework and doing well on tests.

Though there are likely to be some mixed reactions to the change, this group of students were unanimously opposed the ban when Chalkbeat spoke to them at a high school in 2012: