Microsoft Media Server (MMS), a Microsoft proprietary network-streaming protocol, serves to transfer unicast data in Windows Media Services (previously called NetShow Services).
As part of protocol rollover a Windows Media Player version 9, 10, or 11 client opening an "mms://" URL will attempt to connect first with RTSP over UDP and if that fails it will attempt RTSP over TCP.
[4] If using Windows Media Player 11 and an RTSP attempt fails, or if using a previous version of Windows Media Player and MMS fails, a modified version of a HTTP over TCP connection will be attempted.
This modified version is referred to by some third parties as MMSH,[citation needed] and by Microsoft as MS-WMSP (Windows Media HTTP Streaming Protocol).
[6] For several years developers of the SDP Multimedia download-tool reverse engineered the MMS protocol and published unofficial documentation for it.