What is it that mobile phones often receive these short messages for downloading things?

Yes, I received the MMS, but because the mobile phone can't download it, I can only see the word download, but I can't see the MMS content. MMS can only be stored on the server for 48 hours. If you don't download it in time within this time limit, you won't be able to receive it later.

Introduction to MMS:

The English name of MMS is MMS, which is the abbreviation of multimedia messaging service, meaning multimedia messaging service, and is often called MMS. Its biggest feature is that it supports multimedia functions and can transmit comprehensive content and information, including text, image, sound, 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, from mobile phone terminal to Internet or from Internet to mobile phone terminal.