Why does my mobile phone display MMS when sending text messages to others?

MMS is the MultimediaMessagingService of China Unicom. Its biggest feature is that it supports multimedia functions and can transmit comprehensive content and information, including text, images, sounds, data and other multimedia formats. Technically speaking, MMS is not a short message, but with the support of GPRS network and WAP wireless application protocol as the carrier to transmit pictures, sounds, words and other information. MMS service can realize instant multimedia information transmission from mobile phone end to end (including sending to domestic mobile users), from mobile phone terminal to Internet or from Internet to mobile phone terminal.

Simply put, it is a short message that can send pictures, photos and ringtones. We call it "MMS".

So it is very likely that you included the above information in the sending process, which led to the sending of MMS.