AudioCodes Mediant 4000 SBC User Manual page 446

CHAPTER 19 Coders and Profiles
Parameter
'RTCP Feedback'
sbc-rtcp-feedback
[IPProfile_
SBCRTCPFeedback]
'Voice Quality Enhancement'
sbc-voice-quality-
enhancement
[IpProfile_
SBCVoiceQualityEnhancement]
Description
Enables RTCP-based feedback indication in outgoing
SDPs sent to the SIP entity associated with the IP Profile.
The parameter supports indication of RTCP-based
feedback, according to RFC 5124, during RTP profile
negotiation between two communicating SIP entities. RFC
5124 defines an RTP profile (S)AVPF for (secure) real-time
communications to provide timely feedback from the
receivers to a sender. For more information on RFC 5124,
see http://tools.ietf.org/html/rfc5124.
Some SIP entities may require RTP secure-profile
feedback negotiation (AVPF/SAVPF) in the SDP
offer/answer exchange, while other SIP entities may not
support it. The device indicates whether or not feedback is
supported on behalf of the SIP entity. It does this by adding
an "F" or removing the "F" from the SDP media line ('m=')
for AVP and SAVP. For example, the following shows
"AVP" appended with an "F", indicating that the SIP entity
is capable of receiving feedback
m=audio 49170 RTP/SAVPF 0 96
■ [0] Feedback Off = (Default) The device does not send
the feedback flag ("F") in SDP offers/answers that are
sent to the SIP entity. If the SDP 'm=' attribute of an
incoming message that is destined to the SIP entity
includes the feedback flag, the device removes it
before sending the message to the SIP entity.
■ [1] Feedback On = The device includes the feedback
flag ("F") in the SDP offer sent to the SIP entity. The
device includes the feedback flag in the SDP answer
sent to the SIP entity only if it was present in the SDP
offer received from the other SIP entity.
■ [2] As Is = The device does not involve itself in the
feedback, but simply forwards any feedback indication
as is.
Note:
■ As RTCP-based feedback has been defined by the
WebRTC standard as mandatory, the support is
important for deployments implementing WebRTC. For
more information on WebRTC, see WebRTC.
■ RTCP-based feedback is required for the VoIPerfect
feature (see VoIPerfect).
Enables the device to detect speech and network quality
(packet loss and bandwidth reduction) and triggers the
device to overcome the adverse conditions to ensure high
call quality.
■ [0] Disable (default)
■ [1] Enable
Note: The parameter is applicable only to the VoIPerfect
feature (see VoIPerfect).
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Mediant 4000 SBC | User's Manual