SMS

SMS (Short Message Service) is a service for sending and receiving short text messages of up to 160 characters (70 characters in Japanese), addressed to a mobile phone number. Since the world's first SMS was sent in 1992, it has been one of the most widely used means of communication around the world. Its strength is that it needs no internet connection and can be used as long as there is a phone line.

A QR code can store SMS recipient information. By embedding a phone number and a preset message in a QR code, just scanning it opens the message composition screen, and just pressing the send button completes it. This is used for event registration, survey responses, service applications, and so on.

In the field of security, SMS is widely used as a means of two-factor authentication (2FA). This is a method in which, when logging in, you enter a verification code sent by SMS in addition to your password. However, because of the risk of SIM swap attacks (a technique for hijacking a phone number), moving to a more secure authenticator app (such as Google Authenticator) is recommended.