http://www.rfc-editor.org/rfc/rfc6341.txt
RFC 6341: Use Cases and Requirements for SIP-Based Media Recording (SIPREC), K. Rehor, L. Portman, A. Hutton, R. Jain2011-08-01T23:00:00-00:00Recording is typically performed by sending a copy of the session media to the recording devices. This document specifies requirements for extensions to SIP that will manage delivery of RTP media to a recording device. This is being referred to as SIP-based Media Recording. This document is not an Internet Standards Track specification; it is published for informational purposes.