Mayor Brandon Johnson ended the city's contract for the gunshot detection technology two months ago.
Johnson called ShotSpotter ineffective, but 33 out of 50 Chicago City Council members voted to keep the system.
Part of it is still online, but the company stopped sharing data with the city in September.
Ald. Brian Hopkins says a majority of his colleagues already signed an amendment to next year's budget, calling for $15 million to use on another gunshot detection system.
SEE ALSO | Police have responded to gunfire 2.5 minutes faster when alerted by ShotSpotter this year: CPD data