The Media Resource Control Protocol (MRCP) was developed jointly by Cisco Systems Inc., Nuance Communications, and Speechworks Inc. to allow client devices such as personal computers or mobile phones to control 'media resources' such as speech synthesizers and speech recognizers, which typically would be configured to run on IP network-based servers.
MRCP defines the request, responses, and events necessary for controlling the media processing resources and uses a lower level protocol known as the Real Time Streaming Protocol (RTSP) as the means by which MRCP messages are communicated over the IP network. RTSP runs on top of the Transmission Control Protocol (TCP) in order to achieve reliable communication over Ethernet, for example. Note that the current release of Blueworx Voice Response MRCP for State Tables only supports Version 1 of MRCP (which uses RTSP as the lower layer protocol). As well as providing a transport layer for MRCP messages, the RTSP control session is also used to set up the characteristics for the Real Time Protocol (RTP) streams which are used to pass the actual voice data between the MRCP server and the client for Text To Speech. The Blueworx Voice Response MRCP for State Tables implementation conforms to the MRCP V1 RFC 4463 specification.