A Milwaukee PD "critical response vehicle", or surveillance van. (Photo by Isiah Holmes/Wisconsin Examiner)

The Milwaukee Police Department (MPD) is pursuing upgrades to technology used to track phones during investigations. Known as cell site simulators, the formerly murky equipment tracks phones by mimicking cell towers. Once connected to a targeted phone, cell site simulators are able to track the signal, allowing police to locate people. According to city purchasing division records, MPD aims to upgrade and acquire new components and extend a contract for the phone tracking gear by three years. 

The city’s contract with Tactical Support Equipment will be extended until 2028 and increase by $165,000 to $1.45 million. “MPD operating funds will be used,” according to records obtained by the Examiner explaining the purpose for amending the contract. The amendments will cover funds and coverage for two cell site simulators purchased in 2022, the records state. 

A separate section of the purchasing division records explains “this equipment is used on a regular basis to locate suspects and in exigent situations such as critical missing incidents.” It also states, “MPD used this equipment to help support other law enforcement agencies in Wisconsin, law enforcement in other states such as Texas, Ohio, and Michigan, and federal agencies such as FBI and DEA. At this time, MPD is seeking to upgrade the existing equipment, add additional equipment, and add warranty, support and maintenance for the new and upgraded equipment beyond what the department currently has in place. Tactical Support Equipment, Inc. is the only vendor that can support the equipment as the equipment and software is proprietary.”

MPD has used cell site simulators since at least 2010, according to logs the department uses to catalog its use of the gear. For years, the technology was used by MPD’s Fusion Center, an intelligence unit originally created for Homeland Security operations. A group of officers known as the Confidential Source Team – or CS Team – operates the cell site simulators. Logs of the technology’s use show that it’s mostly used to investigate crimes including homicides and shootings and for investigations related to overdoses or firearms. The logs also show the technology is used to locate material witnesses, kidnapping victims, but also for vague reasons like “drugs”, “long term”, or are redacted entirely.

By 2022, when Wisconsin Examiner first interviewed a member of the CS Team, both the team and its gear had been moved from the Fusion Center to MPD’s Special Investigations Division (SID), which focuses on fugitives, felonies and violent crimes. The team’s name invokes the technology’s secretive history. 

The Milwaukee department once signed non-disclosure agreements in order to acquire the technology leading to controversies in 2016, when MPD was accused of hiding use of Stingray-type devices from judges during court proceedings. When asked during a trial about how a person was located, officers used “oddly vague language,” the American Civil Liberties Union (ACLU) of Wisconsin said, even stating that they “obtained information from an unknown source.” Things have changed over time, however. Today, the Milwaukee Police Foundation, which funnels private donations to MPD, publicly lists cell site simulators as among the technologies it helps MPD to purchase.

Like many other law enforcement agencies nationwide, for years MPD utilized phone tracking equipment produced by the Harris Corporation, a multi-billion dollar defense contractor. Harris’ devices were so common that one of its brand names, Stingray, became a common shorthand for all cell site simulators, which are also sometimes called “IMSI catchers.”   

In 2019, MPD purchased a new model from Tactical Support Equipment, a North Carolina-based veteran-owned company which sells everything from K9 camera systems to cables and night-vision cameras. The company does not appear to advertise its cell phone tracking systems on its website. 

Tactical Support Equipment, which did not respond to requests for comment for this story, sold MPD a single cell site simulator in 2019 for $498,900, according to purchasing division records from the time. Later that same year, MPD purchased a C-Hostile Emitter Angle Tracker (C-HEATR), which is a remote handheld mapping device that works together with the cell site simulator. 

Three years later in 2022, MPD upgraded the cell tracking gear by adding a four-channel “5G enabler solution” for $328,700, and a 12-channel portable base station with full 5G coverage (as well as insurance, training, and supporting equipment) for $951,750. 

Responding to questions from Wisconsin Examiner, MPD said that the most recent upgrades will be to “support devices operating in 5G.” The department added that “MPD is the only agency in the area that has a [cell site simulator]. When an agency needs assistance with an investigation and their request falls in line with our operating best practices, we try to provide that agency with assistance.” 

Although cell site simulators are less of an enigma than they used to be, many questions still remain. While MPD states that its technology can only track location, cell site simulators as a family of devices are known to be capable of intercepting calls and text messages, and even more exotic abilities like sending fake short messages to a target phone. In Milwaukee, local activists have long reported strange phone malfunctions and service disruptions which they suspect may be caused by law enforcement surveillance. 

MPD has repeatedly denied responsibility for the claims, and has said in the past that the department’s cell site simulators do not cause malfunctions to target phones. When the Wisconsin Examiner reached out for this story, however, MPD said for the first time that “the equipment already will disrupt service to the target phone when the target phone is located. That disruption is limited to the time it takes for the operator to narrow down the location of the device.” 

The department has also repeatedly stated that its cell site simulators cannot intercept calls or text messages. A different technology known as PenLink is used by MPD for Title III investigations, which involve intercepting content of communications. In responses to Wisconsin Examiner, MPD cited Department of Justice policies and U.S. law which state that “cell site simulator technology must be configured as pen registers, and may not be used to collect contents of any communication.” Wisconsin Examiner reached out to the Wisconsin Department of Justice for more information and has not received a response. 

From 2021 to 2023, Republicans introduced bills that would have changed  how pen registers are defined in Wisconsin. Supporters of the bills, which did not pass, said that they would allow law enforcement to pursue pen registers for social media. Telecommunications experts, however, warned that the bills could open a “back door” for police to use cell site simulator devices in ways not well understood by judges or the public. 

There have been more calls for more oversight of police surveillance in Milwaukee recently, with local activists pushing for  Community Control Over Police Surveillance (CCOPS) ordinances. Over two dozen U.S. cities have already passed such ordinances, which provide more transparency about the purchase and use of surveillance technologies by police departments. MPD stresses that it uses cell site simulators in accordance with DOJ policy “and only after a court order is granted in cases that are not exigent,” the department said in a statement. “There is a process in place in which utilization of the equipment is only done with supervisory approval and oversight.”

State Rep. Ryan Clancy asks questions of a witness testifying at a public hearing on April 10, 2025, about a bill placing to restrictions on the process of qualifying for Medicaid. (Wisconsin Examiner photo)

Rep. Ryan Clancy (D-Milwaukee) has distributed co-sponsorship memos promoting a package of bills aimed at tamping down police violence and surveillance. Dubbed the “Freedom From Fear” package, the bills focus on facial recognition technology, police training and accountability. 

Residents in local Wisconsin communities have called for oversight of police surveillance, including facial recognition technology, and some have raised concerns about the surge in federal operations and deployment of military forces to cities around the country. Clancy’s  proposals would:

• Require the decertification of law enforcement who violate “basic regulations on uses of force, among other standards set by the Law Enforcement Standards Board”.
• Prohibit the use of facial recognition technology, which is known to incorporate artificial intelligence;
• Ban the use of Automatic License Plate Readers, which a press release by Clancy’s office states are  vulnerable to hacking, despite being used to track and monitor thousands of vehicles nationwide,
• Prohibit law enforcement from requesting, obtaining, or receiving access to an individual’s personal data in exchange for payment or a thing of value and without a warrant,
• Set clear policies around releasing body camera footage depicting officer-involved deaths, with a focus on delays which could give police “the motive and opportunity to edit or delete footage,”
• Prohibit police trainings that include content on “excited delirium,” which the press release describes as “a nonscientific, nonmedical term often used to justify police violence and other abuses of authority,” 
• And prohibit “warrior-style training” methods among law enforcement which could lead to “unnecessary injury and death, in favor of aikido training focused on self-defense, de-escalation, and the disarming of threats”.  

In Milwaukee, civil liberties advocates and community activists have drawn more attention to concerns around surveillance by the Milwaukee Police Department (MPD), with a particular focus on license plate readers and facial recognition technology. 

Critics of the two kinds of tech have expressed concerns over the technology’s use without a warrant and their ability to gather information on numerous people who are not the target of any particular investigation. Recently, Wisconsin Examiner also found that several Wisconsin law enforcement agencies utilizing Flock license plate readers entered vague reasons for using the network of cameras. 

Facial recognition technology presents its own unique challenges. Questions have been raised about the technology’s ability to accurately detect and identify faces, particularly people of color. Earlier this summer, MPD announced that it was considering acquiring facial recognition technology from the company Biometrica, in exchange for providing the company with 2.5 million images and records related to people who’d passed through Milwaukee’s criminal justice system, including those who had not been convicted of a crime. In June, as the sheriff’s office began to explore a similar deal, the Milwaukee County Board of Supervisors joined calls to regulate facial recognition technology. 

“In this critical moment, as military forces take over cities across the United States one by one, at President Trump’s whim, we cannot continue investing more public resources and power in unaccountable law enforcement,” Clancy said in a statement. “As state legislators, we have the elected duty and authority to check government overreach in Wisconsin — that overreach is at its most dangerous when done in secret, while armed, and in cooperation with an increasingly openly fascist President.”

Clancy blasted MPD and other nearby law enforcement agencies in his statement for “giddily trading the data of hundreds of thousands of people for access to technology that will let them exploit, and inevitably misuse, the same data.” He called the technology “untested and unregulated” and questioned Biometrica’s ability to secure the data which it collects. 

Meanwhile, President Trump has elevated Immigration and Customs Enforcement as the administration’s premiere federal law enforcement agency, with an enhanced budget that surpasses the military spending of most of the nations  in the world. Trump advisor Stephen Miller also recently  threatened to “identify, disrupt, dismantle and destroy” left-wing movements and organizations, using language reminiscent of the COINTEL PRO intelligence programs run by the FBI for decades under J. Edgar Hoover. During the George Floyd protests of 2020, there were numerous reports of police surveillance and intelligence gathering operations.

“This bill package will prevent this ongoing abuse of sensitive data, without oversight, that MPD and other law enforcement agencies have simply given themselves permission to collect and misuse,” Clancy said in his statement. “We won’t  heal the damage done, or move forward, without securing the kind of basic protections we’re proposing today. These bills are a start, but an important one.”