Racks of mobile phones, SIMs, and cellular modems make up today's SIM farms, which are often rented to cybercriminals to carry out automated attacks worldwide. Just because a text message appears to have been sent from a local number doesn't mean it actually was, and unfortunately, it is this access to local telecom infrastructure that many scammers rely on today when trying to dupe you into trusting the fake messages and calls they send.

A SIM farm is a network of hundreds, even thousands, of mobile SIM cards -- backed by hardware such as modems and handsets -- that operate simultaneously to perform a variety of tasks.

This might bring to mind cryptocurrency mining farms, where high volumes of computing hardware and huge amounts of electricity are used -- sometimes illegally -- to mine cryptocurrency. SIM farms, too, require dedicated hardware and are set to perform tasks, but instead of focusing on crypto or other digital assets, they're often used as communication systems.

SIM farms themselves are not necessarily malicious. For example, businesses may use them for telecom-related testing, measuring, and scaling; developers may use them to conduct mobile app tests, and they could also be used for legitimate bulk business messaging.