In the recordings heard in the Brooklyn courtroom, Guzman was referred to as "boss" and "sir" by different callers, whom he instructed on dealings with Mexican authorities and troops. In one phone call from 2011, Chapo told a lieutenant known only as "Cholo" to "take it easy with the police."
"You told us to be a wolf, to act like a wolf," Cholo responded. "That's how I like to do it."
"Just reprimand them," Chapo ordered. "Don't beat them anymore."
In one call, Guzman is heard discussing the sale of methamphetamine in the U.S. He asks one correspondent: "What can you tell me ... do you still have customers in Los Angeles?"
Later in the conversation, the person Guzman is talking to tells him: "My brother goes to 52 states."
Prosecutors said the FBI was able to confirm Guzman's voice by using video from an interview he conducted with actor Sean Penn for Rolling Stone magazine in October 2015, after Guzman had escaped from a Mexican prison for a second time. He was captured in early January 2016, shortly after the interview was published, following a shootout between cartel members and Mexican marines.
An FBI special agent testified that the bureau hacked into the Sinaloa cartel's encrypted communications system with the help of a technician who turned government informant.
Guzman is facing conspiracy charges at the ongoing trial in federal court in Brooklyn. He was extradited to the U.S. in 2017 to face trial. Guzman's lawyers say he's being framed by co-operators who are the real culprits in a vast drug conspiracy.
Fox News' Marta Dhanis and The Associated Press contributed to this report.