New York is becoming the first major city in the U.S. to offer free phone calls from jails.

According to the New York Times, Mayor Bill de Blasio signed a bill into law Monday.

It takes effect in nine months.

Local calls from Rikers Island currently cost 50 cents for the first minute and 5 cents for each additional minute.

About three quarters of people in the city's jails have not been convicted of a crime and are there awaiting trial. Many are poor.

The move is part of a nationwide push from prison-rights groups, public defenders and prisoners' families to limit private companies from profiting off incarceration.

The president of the correction officers' union says free phone calls could aid gangs that run operations from inside the jails.