What is a 'SIM bank' that uses more than 100,000 SIM cards to make nuisance calls and shut down base stations?

Ahead of the start of the United Nations General Assembly, the Secret Service announced that it had dismantled a 'SIM bank' in the New York area, comprising more than 300 SIM servers and 100,000 SIM cards, capable of making anonymous nuisance calls and disabling cell towers.

US Secret Service dismantles imminent telecommunications threat in New York tristate area | United States Secret Service

The Secret Service dismantled a network of more than 300 SIM servers and 100,000 SIM cards in the New York-area that were capable of crippling telecom systems and carrying out anonymous telephonic attacks, disrupting the threat before world leaders arrived for the UN General… pic.twitter.com/sZKUeGqvGY

— US Secret Service (@SecretService) September 23, 2025

NYC Telecom Raid: What's Up With Those Weird SIM Banks?
https://tedium.co/2025/09/23/secret-service-raid-sim-bank-telecom-hardware/

The Secret Service announced that it has dismantled an electronic network used to launch communications attacks against high-ranking U.S. government officials. The network, which consisted of more than 300 SIM servers and 100,000 SIM cards, 'posed an imminent threat to security operations,' according to the Secret Service.

Some of the seized equipment looks like this.

There was a mountain of debris left behind after the SIM cards used in the devices had been removed.

A device containing a large number of SIM cards. The Secret Service calls it a 'SIM box.'

A 'SIM bank' with racks full of 'SIM boxes.'

According to the Secret Service, the SIM bank could be used to launch a variety of communications attacks, including making anonymous threatening phone calls, shutting down cell towers, and launching denial-of-service (DoS) attacks.

Forensic investigations are ongoing, but initial analysis indicates cell phone communications between a 'nation-state threat actor' and 'individuals known to federal law enforcement.'

According to the newsletter Tedium, the device seized by the Secret Service was an 'SMS/Voice Gate Solution' manufactured by Chinese company Ejoin Technology, which sells for $3,730 (approximately 554,000 yen) each.

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In fact, a joint operation involving seven African countries uncovered a fraud scheme using this type of 'SIM bank,' resulting in the arrest of 306 suspects and the seizure of 1,842 devices.

More than 300 arrests as African countries clamp down on cyber threats