For heroin dealers, the cell phone number is the lifeline of the business, ensuring a continuous flow of customers and cash that can top $10,000 in a single day.
Dealers and their associates, intent on preserving their specific phone numbers, often have contingency plans in place to transfer well-known numbers to a new phone as a way to evade law enforcement and keep profits soaring.
But a new tactic used by Wisconsin police – called a "seize and freeze" order – seeks to disrupt this practice, allowing authorities to freeze such numbers and render them useless.
Law enforcement sources told Fox News the strategy is an additional tool in fighting the deadly trade in Milwaukee, where heroin dealing is hugely profitable, and could prove useful nationwide.
"Identifying and exploiting command-and-control phones, as well as interrupting the availability of street level 'distribution' phones are a couple of techniques that make selling dangerous substances more difficult," said Robert Bell, the agent who oversees U.S. Drug Enforcement Administration operations in Wisconsin.
Bell, who was unable to disclose details on specific law enforcement tactics, told Fox News in a statement that authorities will use "any and all effective and legal approaches to disrupt and dismantle violent drug trafficking organizations and their activities."
The Milwaukee Police Department declined to comment on the "seize-and-freeze" order as well as specific cases in which the tactic has been used.
According to a report by the Milwaukee Journal Sentinel, the first "seize-and-freeze" order in the state was carried out earlier this year. In that case, authorities dismantled a number being used by a group known as Big Money Addicts, or BMA, according to the paper, citing court records.
"The BMA relied heavily on the cellular phone as the core means of communications of their business," reads a copy of the warrant, obtained by the paper. "Due to the high profits from selling narcotics, dealers will retain these phone numbers at all costs."
Law enforcement sources said the high-rolling dealers use prepaid cellphones and pick numbers that are easy to memorize – often printing them on business cards with fictitious business names.
If a dealer and cell phone are apprehended, an associate transfers that number to a new phone to ensure the business continues booming.
"It's often the No. 2 guy who is still out there or a girlfriend visiting [an inmate]" one law enforcement source told Fox News. "It's someone who still has access to the source of supply."
Heroin-related overdose deaths have more than quadrupled since 2010, according to the Centers for Disease Control and Prevention. From 2014 to 2015, heroin overdose death rates increased by 20.6 percent, with nearly 13,000 people dying in 2015. In 2015, males ages 25 to 44 had the highest heroin death rate at 13.2 per 100,000, which was an increase of 22.2 percent from 2014.
The CDC lists 11 states as having a significant increase in drug overdose death rates involving heroin from 2014 to 2015: New York, Ohio, Connecticut, Georgia, Illinois, Maryland, Massachusetts, North Carolina, South Carolina, Tennessee and Virginia.
Bell said Wisconsin has seen an alarmingly high increase as well.
"The substantial increase in the supply of deadly illicit fentanyl substances, in combination with the existing prescription opioid pain killer and heroin crisis, has caused already high overdose death numbers to sky rocket in Wisconsin," he said.
"Steps are being taken to reduce availability and to raise the public’s awareness of the hazards these toxic substances pose to our communities and families," Bell said. "Fentanyl is an immediate and severe public safety concern. Anyone with an opioid or heroin dependence problem should seek help from medical professionals, rather than buying unknown, deadly substances from street dealers.”