Crooks have stolen tens of millions of dollars and other valuable commodities from thousands of consumers via “SIM swapping,” a particularly invasive form of fraud that involves tricking a target’s mobile carrier into transferring someone’s wireless service to a device they control. But the U.S. Federal Communications Commission (FCC), the entity responsible for overseeing wireless industry practices, has so far remained largely silent on the matter. Now, a cadre of Senate lawmakers is demanding to know what, if anything, the agency might be doing to track and combat SIM swapping.