Frustrated with students’ use of cell phones in class, a British Columbia high school principal took action last week  — he bought a signal jammer online, and plugged it in at his office.

Unfortunately for him, jamming cell phones is illegal under Canadian law.

Principal Steve Gray installed the gizmo on Tuesday. By the end of the day Wednesday rumors of the jammer’s existence were beginning to spread. On Thursday, more than a quarter of Port Hardy Secondary School’s 343 students skipped classes in protest, and on Friday morning Gray took the jammer offline.

“We did our research on the Internet,” said Amber Wright, an eleventh grader who helped organize the student strike. “Breaking the law is not a good way to send a message.”

Students said that their parents use the cell phones to keep in touch with them, and that relaying messages through the school is slow and cumbersome. 

Principal Gray told the Toronto Globe and Mail that he himself carries a cell phone at school, but that he only uses it in emergencies.