MMS, which stands for Multimedia Messaging Service, is a standard for wireless telecommunications systems, developed as an evolution of Short Message Service (SMS).

It enables the transmission of messages that, in addition to just text as included in SMS, may include multimedia objects such as audio, video, images and rich text. MMS, along with such messaging systems as SMS, Mobile E-mail and Mobile Instant Messaging, is included as a standard in GSM/GPRS and CDMA cellular networks, and it has also been designed to work with mobile packet data services, examples of which include GPRS and 1xEV-DO.

The 3rd Generation Partnership Project (3GPP), a standards organization focused on standards for the UMTS/GSM networks, 3GPP2, a standards organization focused on specifications for CDMA2000 networks, and Open Mobile Alliance (OMA), a standards organization focused on the development of specifications for wireless telecommunications networks, are three organizations that play a key role in the standardization of MMS.

There are three stages for the MMS standards. The first stage is Requirements (3GPP TS 22.140), the second is Functions (3GPP TS 23.140) and the third is Technical Realizations, a stage that 3GPP and 3GPP2 have delegated to the OMA.

MMS has two modes of delivery, both of which are handset-dependent. The first, immediate delivery, is the reception of an MMS notification by an MMS client on the mobile phone, followed by the immediate retrieval of the MMS message from the Multimedia Messaging Service Center (MMSC) responsible for sending the notification.

The subscriber then receives an alert about a new MMS message after the retrieval. The second mode of delivery, which is deferred delivery, is when the subscriber can decide if and when to retrieve the MMS message after receiving an alert from the MMS client.

MMS submissions and retrieval requests both occur with an HTTP request, responded to by the MMSC by transmitting the MMS message in an HTTP response to the MMS client. After this, the subscriber receives an alert on the availability of the MMS message.

One quality differentiating the two modes of delivery is that immediate delivery hides the network latencies from the subscriber. Deferred delivery, on the other hand, does not.

MMS requires that a number of handset parameters are set in order to perform well. Should there be poor handset configuration, this could prove to be a point of failure for MMS subscribers.

At present, mobile operators are considering new device management technologies which employ over-the-air programming (OTA) to deliver the necessary settings for data services such as MMS and WAP.

MMS messages may include one or more multimedia objects; however, the content types must conform to the MMS Standards. To avoid format incompatibility, all mobile handsets should follow the standards defined by the OMA.

The recipient MMSC is also responsible for content adaptation, such as image resizing and audio codec transcoding. The compatibility among a network of MMS users is dependent on whether or not content adaptation is supported by a network operator.