Text messaging sends short text messages between mobile phones. It is also called SMS. The first SMS was sent in 1992. It was 15 characters. It was not expected to be popular. Now trillions are sent every year. It is the most widely used mobile service after voice.

SMS uses the signaling channel of the cellular network. It does not need a data connection. It works on any phone. Messages are limited to 160 characters. Longer messages are split. SMS is store-and-forward. If the recipient is offline, the message is held and delivered later.

Text messaging types

• SMS: 160 characters, no media
• MMS: media, larger
• RCS: rich messaging, read receipts
• OTT: WhatsApp, iMessage, Telegram

Text messaging is being replaced by messaging apps. They offer more features. They work over data. They are free. But SMS is universal. It works on every phone. It does not need an app. It is used for two-factor authentication, alerts, and emergencies. SMS is old. It is not gone.