This appendix describes multicast recording and includes the following sections:
All IPICS voice traffic that pertains to interoperability is represented by a channel, radio or VTG, each of which are configured with a multicast address. All voice traffic appears on its respective multicast address, even if a participant has joined via a unicast session (SIP). Furthermore, all voice traffic appears in the form of Real Time Protocol (RTP) packets using G.711 or G.729 codecs.
A third party voice recording system can be used to record voice traffic on each multicast address. It can either be configured to continuously record, or be triggered to record by the presence of RTP packets. The recording system must manage the timestamp, datestamp, and duration information. Some recording systems are capable of detecting other external events, such as ring, off-hook, and contact closure. These systems should be configured so that activities start when those events happen.
Some devices support talker ID, which requires RTCP. If talker ID is not functioning properly, make sure that your network is configured to support RTCP.
For serial controlled donor radios and ISSI gateways, certain metadata associated with the talk spurt is available during the call. This is represented within a RTP packet of payload type 109. The packet payload is in the following format:
Other data related to the radio or gateway is also present in this packet and is not relevant to the media. The recording system must be configured to gather these radio control packets.
Metadata related telephone related talk sessions are available in IPICS/IPPE activity logs and Call Manager logs. The recording system must correlate RTP sessions with these logs. For detailed telephony audio recording capabilities, the recording system can integrate directly with Cisco Unified Communication Manager (CUCM).