Media Loopback; Media Loopback Configuration - Yealink SIP-T2 Series Administrator's Manual

Administrator's Guide for SIP-T2 Series/T4 Series/T5 Series/CP920 IP Phones
Values
Default Blank

Media Loopback

The SIP RTP media loopback can be used to make test calls to verify the media path between the phone and server.
RTP packets are looped back toward the source device. In a voice loopback call, an echo is heard at the device ori-
ginating the call.
For more information on media loopback, refer to
Topic

Media Loopback Configuration

Media Loopback Configuration
The following table lists the parameters you can use to configure media loopback.
Parameter sip.loopback.enable
It configures the loopback role for the phone.
Description
Note: After the phone accepts the loopback call, the mute feature will be automatically activated on the
phone.
0-Loopback-Mirror, the server initiates a loopback call, and the phone accepts the call and mirrors
(echoes) all received media back to the server.
Permitted
Values
1-Loopback-Source, the phone can initiate a loopback call as a media source or receive a loopback call as
a loopback mirror.
Default 0
Parameter sip.loopback_type
Description It configures the media loopback type.
1-rtp-media-loopback, the packet received by loopback mirror is re-encoded based on the SDP nego-
tiation. The re-encoded content is returned to the loopback source as an RTP packet with payload type
corresponding to the re-encoding format.
Permitted 2-rtp-pkt-loopback, the RTP payload is re-encapsulated and the RTP packets are looped back with a new
Values payload type and format. This type of loopback applies to the encapsulated and direct packet loopback.
Any type of encoding-related functions must not be part of this type of loopback path.
3-rtp-media-loopback & rtp-pkt-loopback, the answer must include only one of these two loopback
types and should give preference to the first loopback-type in the SDP offer.
Default 3
Parameter sip.pkt_loopback_mode
It configures the encapsulation mode of incoming RTP packet.
Description
Note: It works only if "sip.loopback_type" is set to 2 (rtp-pkt-loopback).
1-encapsulated packet loopback, the entire incoming RTP packet is encapsulated as payload within an
Permitted
outer RTP packet. The loopback source can generate statistics for one-way path performance up to the
Values
RTP level for each direction of travel.
480
RFC 6849.
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