Microsoft Media Server

Microsoft Media Server (MMS), a Microsoft proprietary network-streaming protocol, serves to transfer unicast data in Windows Media Services (previously called NetShow Services). MMS can be transported via UDP or TCP. The MMS default port is UDP/TCP 1755.[1]

Microsoft deprecated MMS in favor of RTSP (TCP/UDP port 554) in 2003 with the release of the Windows Media Services 9 Series, but continued to support the MMS for some time in the interest of backward compatibility. Support for the protocol was finally dropped in Windows Media Services 2008.[2]

As of 2012 Microsoft still recommends[2] using "mms://" as a "protocol rollover[3] URL". 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. After an RTSP attempt fails, Windows Media Player versions 9 and 10 will attempt MMS over UDP, then MMS 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, and by Microsoft as MS-WMSP (Windows Media HTTP Streaming Protocol).[5] The uniform resource identifier (URI) scheme mms has also been proposed to be used for the unrelated Multimedia Messaging Service (MMS) protocol.[6]

For several years developers of the SDP Multimedia download-tool reverse engineered the MMS protocol and published unofficial documentation for it. However, Microsoft finally released the protocol specification in February 2008.[7]