Some attendees at the RSA Conference in April received a message announcing the registration to a new cell network. The SMS came from a fake GSM tower that accepted registrations from any endpoint with a SIM card in its vicinity, including Internet-of-Things devices. This type of threat works better in crowded places to ensure service through a weaker technology, like 4G, in a crowded area it may end up using a less secure one. Even if the gadget is compatible with a newer cellular technology, or a newer 4G. In this context, some obstacles act as a deterrent for an inexperienced adversary.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/rogue-gsm-towers-internet-things-devices/