MMS

Where the SMS is limited to text, the MMS accommodates image, audio, video or a fuller text. It doesn't travel through the signalling channels but uses a data connection, which changes everything about its delivery.

This detour has very concrete effects: the MMS requires an active data connection and a correctly configured mobile, its billing follows its own rules, and its weight remains capped by the operator, generally at a few hundred kilobytes. That's why the text SMS remains the most universal format and the simplest to send.