The SBC Core supports RFC1889/2327 where RTP runs on even UDP ports and RTCP runs on next higher odd UDP ports. RFC 3605 defines the use of the RTCP attribute to document the RTCP port used for media stream when that port is not the next higher (odd) port number following RTP port described in the media line.

The SBC supports the peer's published RTCP media attribute which contains port information for RTCP packets (SR/RR) for voice streams. If the peer sends an IP address in this attribute it must be same as the media connection address.

If a peer publishes more than one media lines (video cases) with corresponding RTCP attributes, only RTCP attribute corresponding to audio is used and the default behavior (RTP +1) shall be kept for other streams.

If a peer warrants sending RTCP attribute for inter-working reasons, this RTCP attribute can be published in the outgoing SDP with port as RTP + 1, provided corresponding per Trunk Group level flag in IP Signaling profile is enabled (or Local Policy flag). This behavior is independent whether the incoming SDP is having the RTCP attribute or not.

 

This feature is only supported with ERE and EMA (excludes PSX). It is also not supported for Direct Media, Late Media, GW and H.323 protocol interworking scenarios.

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