Over time, this FBI-run app grew to service more than 12,000 encrypted devices to over 300 criminal syndicates operating in more than 100 countries, including Italian organised crime, outlaw motorcycle gangs, and worldwide drug trafficking organisations.
Using the messages, USA court papers say, the authorities have opened a barrage of global investigations into drug trafficking, money laundering and "high-level public corruption".
He said the app access had given law enforcement "an edge that it had never had before", but added the platform was just one of many messaging apps favoured by organised crime gangs. In fact, the agency had sent the Anom devices into the black market in the first place.
On top of the arrests police in numerous jurisdictions seized eight tons of cocaine, 250 guns and £34 million in cash and cryptocurrencies as well as several luxury cars.
"The very devices that criminals use to hide their crimes were actually a beacon for law enforcement", Randy Grossman, the acting US attorney in San Diego, said at a news conference.
In total over the course of the three years, more than 9,000 police officers across 18 countries were involved in maintaining the operation.
On Monday alone, they seized 104 firearms, including a military-grade sniper rifle, as well as nearly A$45 million ($35 million) in cash, including A$7 million from a safe buried under a garden shed in a suburb of Sydney.
Among them are drug dealers in the UK. The phones could only send messages to another device that had the app and criminals needed to know another criminal to get a device.
Australian officials said they had revealed the operation on Tuesday because of the need to disrupt unsafe plots now in motion and because of limited time frames for legal authorities invoked to intercept the communications.
Investigators in Canada, where Phantom Secure was based, and Australia had known it was a preferred communications device for criminal organizations but had struggled to crack the case. Its CEO, Vincent Ramos, pleaded guilty; other company leaders were also indicted. As the Australian authorities were ahead of the Federal Bureau of Investigation in getting a legal framework in place to snoop on these conversations, the Oz cops were first in examining the chatter - albeit just conversations involving users either in Australia or with a nexus to it.
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Anom also had a built-in advantage: Those running it were able to listen - directly - to the target audience and give users what they wanted.
However, AN0M was forged in a joint operation by Australian and United States federal law enforcement, and was deliberately and surreptitiously engineered so that agents could peer into the encrypted conversations and read crooks' messages.
These devices were distributed organically and became popular among criminals.
Law enforcement agencies from Sweden to New Zealand described the operation as having an important effect.
New Zealand Police said: "The closure of these two encrypted communications platforms has created a huge void in the crypto communications market".
Australian police said the devices were initially used by alleged senior crime figures, giving other criminals the confidence to use the platform.
The Australian is said to be the head of an global drug cartel and has been on the run from authorities for the past decade.
So those included drug smuggling, money laundering and planned killings.