SMS / MVNO carry and international voice call / IRSF fraud is alive and well. Probably bigger than ever. Apps which use SMS 2FA and voice 2FA are highly vulner

SMS / MVNO carry and international voice call / IRSF fraud is alive and well. Probably bigger than ever. Apps which use SMS 2FA and voice 2FA are highly vulnerable - scammers will create fake accounts and request recovery over and over, either to pump SMS into MVNOs they partner with, or pump voice calls through to international premium rate numbers they control. Since the whole thing is a legacy system built with little mind to hostile actors, most phone networks aren't well equipped to distinguish from these uses and legitimate use, even though it doesn't seem like it should be particularly hard. Unfortunately, one big-hammer solution is often to just ban countries outside of an application's target market from the auth flow, which isn't great from a sociopolitical standpoint.