MMS is the Multimedia Messaging System. It is the evolution of SMS, the Short Messaging System, a system for sending and receiving short text-based messages. MMS is the next generation upgrade for SMS in 3G networks. However, MMS does not require a 3G network. MMS can function under a 2G or 2.5G network, and handsets and networks that support MMS are expected by the end of 2001.

The Multimedia Messaging Service (MMS), as its name implies, is intended to provide a rich set of content to subscribers in a messaging context. It supports both sending and receiving of such messages by properly enabled client devices.

The Multimedia messaging service is viewed as a non-real-time delivery system. This is comparable to many messaging systems in use today. Prime examples include traditional email available on the Internet and wireless messaging systems such as paging or SMS. These services provide a store-and-forward usage paradigm and it is expected that the MMS will be able to interoperate with such systems. Real-time messaging also exists in various forms. For example, instant messaging available from various vendors or various chat services (e.g. text, voice) are becoming popular. Such services are not currently supported with the MMS system but may be considered for future releases.

Multimedia Messaging Service (MMS) is a system application by which a WAP client is able to provide a messaging operation with a variety of media types. The service is described in terms of actions taken by the WAP MMS Client and its service partner, the MMS Proxy -Relay, a device which operates as a WAP Origin Server for this specialized service. Additional service aspects are supported by the MMS Server as well as other messaging servers, such as an email server and wireless messaging systems (e.g. SMSC). This specification defines application-level protocol activities that take place to realize the MMS service within the WAP environment.