MRCP uses a similar style of clear-text signaling as HTTP and many other Internet protocols, in which each message contains 3 sections: a first-line, a header and a body.
Like HTTP, MRCP uses a request (usually issued by the client) and response model.
Responses may simply acknowledge receipt of the request or give other information regarding its processing.
For example, an MRCP client may request to send some audio data for processing (say, for speech recognition), to which the server could respond with a message containing a suitable port number to send the data, since MRCP does not have support for audio data specifically as this would have to be handled by some other protocol, such as Real-time Transport Protocol (RTP).
MRCP has been adopted by a wide range of commercial speech servers, such as Verbio Technologies, Skit.ai's VIVA, Microsoft Speech Server, LumenVox Speech Engine, ReadSpeaker speechServer MRCP, Nuance Recognizer and Vocalizer, Sestek TTS, Sestek Call Steering as well as commercial Interactive Voice Response software such as Blueworx Voice Response..