AudioCodes Mediant 4000 SBC, User Manual

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CHAPTER 19 Coders and Profiles
Mediant 4000 SBC | User's Manual
Parameter Description
RTP redundancy is useful when there is packet loss; the
missing information may be reconstructed at the receiver
side from the redundant packets.
■ [0] As Is = (Default) The device does not interfere in the
RTP redundancy negotiation and forwards the SDP
offer/answer (incoming and outgoing calls) as is without
interfering in the RTP redundancy negotiation.
■ [1] Enable = The device always adds RTP redundancy
capabilities in the outgoing SDP offer sent to the SIP
entity. Whether RTP redundancy is implemented
depends on the subsequent incoming SDP answer
from the SIP entity. The device does not modify the
incoming SDP offer received from the SIP entity, but if
RTP redundancy is offered, it will support it in the
outgoing SDP answer. Select the option if the SIP
entity requires RTP redundancy.
■ [2] Disable = The device removes the RTP
redundancy payload (if present) from the SDP
offer/answer for calls received from or sent to the SIP
entity. Select the option if the SIP entity does not
support RTP redundancy.
Note:
■ To enable the device to generate RFC 2198 redundant
packets, use the IPProfile_RTPRedundancyDepth
parameter.
■ To configure the payload type in the SDP offer for RTP
redundancy, use the RFC2198PayloadType.
'RTCP Mode'
sbc-rtcp-mode
[IPProfile_SBCRTCPMode]
Defines how the device handles RTCP packets during call
sessions for the SIP entity associated with the IP Profile.
This is useful for interworking RTCP between SIP entities.
For example, this may be necessary when incoming RTCP
is not compatible with the destination SIP entity's (this IP
Profile) RTCP support. In such a scenario, the device can
generate the RTCP and send it to the SIP entity.
■ [0] Transparent = (Default) RTCP is forwarded as is
(unless transcoding is done, in which case, the device
generates RTCP on both legs).
■ [1] Generate Always = Generates RTCP packets
during active and inactive (e.g., during call hold) RTP
periods (i.e., media is 'a=recvonly' or 'a=inactive' in the
INVITE SDP).
■ [2] Generate only if RTP Active = Generates RTCP
packets only during active RTP periods. In other words,
the device does not generate RTCP when there is no
RTP traffic (such as when a call is on hold).
Note: The corresponding global parameter is
SBCRTCPMode.
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