23.1403GPPFunctional descriptionMultimedia Messaging Service (MMS)Stage 2TS
5.1.1 MMS User Agent operations
The MMS User Agent shall provide the following application layer functionalities:-
- the MM composition
- the MM presentation
- the presentation of notifications to the user
- the retrieval of MMs (initiate MM delivery to the User Agent)
The MMS User Agent may provide additional application layer functionalities such as:-
- the signing of an MM on an end-user to end-user basis
- the decryption and encryption of a MM on an end-user to end-user basis
- all aspects of storing MMs on the terminal and/or USIM
- the handling of external devices
- the user profile management
This optional list of additional functionalities of the MMS User Agent is not exhaustive.
5.1.2 Minimum set of supported formats
Multiple media elements shall be combined into a composite single MM using MIME multipart format as defined in RFC 2046 . The media type of a single MM element shall be identified by its appropriate MIME type whereas the media format shall be indicated by its appropriate MIME subtype.
In order to guarantee a minimum support and compatibility between multimedia messaging capable terminals, the following media formats shall be at least supported.
Minimum set of supported media type Text formats:-
- plain text. Any character encoding (charset) that contains a subset of the logical characters in Unicode  shall be used (e.g. US-ASCII , ISO-8859-1, UTF-8, Shift_JIS, etc.).
Unrecognised subtypes of "text" shall be treated as subtype "plain" as long as the MIME implementation knows how to handle the charset. Any other unrecognised subtype and unrecognised charset shall be treated as "application/octet- stream".
In order to guarantee SMS interoperability, SMS 3G TS 24.011  RP-DATA RPDU encapsulation defined in chapter 7.3.1 shall be supported. MIME type application/x‑sms shall be used for this purpose.
Note: SMS MIME type shall be used as soon as the MIME registration has been completed.
To ensure interoperability with formats widely used e.g. in the internet community the support of the following formats or codecs is suggested:-
Suggested formats or codecs for media type Audio:-
- AMR / EFR; organised in octet format as specified in 3G TS 26.101 and 3G TS 26.101 Annex A 
- MP3 
- MIDI 
- WAV 
Suggested formats or codecs for media type Image :-
- JPEG 
- GIF 89a 
Suggested formats or codecs for media type Video:-
- MPEG 4 (Visual Simple Profile, Level 1) 
- ITU-T H.263 
- Quicktime