SMS (Short Message Service) is a service for sending and receiving short text messages using phone numbers as addresses. Since the world's first SMS was sent in 1992, it has been a standard feature of mobile phones worldwide. The basic limit is 70 full-width characters (160 half-width) per message, though concatenated sending now allows up to 670 full-width characters.
SMS's greatest feature is that it requires no app installation and can be sent to anyone whose phone number you know. This high deliverability has led to its widespread adoption for identity verification (two-factor authentication) one-time passwords, financial transaction notifications, delivery notifications, and appointment reminders.
Sending fees vary by carrier but are approximately 3-33 yen per domestic SMS (volume-based by character count). Receiving is free. Unlike messaging apps such as LINE, SMS uses the phone network rather than data, so it works even without internet connectivity. This characteristic makes SMS relatively reliable during disasters when internet is down, serving as an effective means of safety confirmation. The successor standard RCS has emerged, offering features SMS lacks such as image sending and group chat, all phone-number-based.
However, smishing fraud exploiting SMS has surged. Impersonating financial institutions or delivery companies, fake messages like "You have a delivery" or "Your account has been restricted" direct victims to fraudulent websites. Legitimate companies never request passwords or account information via SMS, so never tap links carelessly. Review the latest techniques and countermeasures in the smishing countermeasures guide.