SMS is used for login codes and alerts, but text messages can be intercepted, spoofed, or redirected through phone-account attacks.
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Background for this topic.
SMS (Short Message Service) is a standardized mobile-network service for sending short text messages between phone numbers. It is widely used for person-to-person communication, service notifications, and one-time authentication codes, but messages are generally not end-to-end encrypted and may be visible to mobile operators or infrastructure handling delivery.
Security concerns include smishing—phishing delivered by text—along with sender-ID spoofing, malicious links, and social engineering. Account recovery and SMS-based multi-factor authentication can also be undermined when an attacker takes control of a phone number through SIM swapping, abuses carrier processes, or exploits signaling-system weaknesses. Organizations should avoid treating SMS as a high-assurance authentication factor where stronger options are practical, restrict sensitive content in texts, monitor number-change and authentication events, and train users to verify unexpected messages through a trusted channel.
Making the option available only to paid subscribers — while also claiming SMS authentication is broken — doesn't make sense, some say. Is it a cash grab?