McNulty arranges a meeting with Fitz to discuss the possibility of doing exactly what Freamon suggested. McNulty asks Fitz about equipment that picks up numbers dialed on cellular phones nearby. Fitz tells McNulty that the equipment he needs is already available to city police because of a Homeland Security grant. McNulty retrieves the machine from the police department basement. McNulty and Freamon set up the machine in a vacant apartment opposite Stringer's photocopying business. They record all cell phone numbers using the nearby tower for signal. They narrow the field back at the detail office by tying specific times that Stringer would be on the phone to their data by monitoring calls to Shamrock.