CHAPTER57 Reporting Information to External Party
Mediant 1000 Gateway & E-SBC | User's Manual
57 Reporting Information to External Party
This section describes features for reporting various information to an external party.
Configuring RTCP XR
RTP Control Protocol Extended Reports (RTCP XR) is a VoIP management control that defines a
set of metrics containing information for assessing VoIP call quality and for diagnosing problems.
RTCP XR (RFC 3611) extends the RTCP reports defined in RFC 3550 by providing additional VoIP
metrics (Quality of Experience). RTCP XR information publishing is implemented in the device
according to RFC 6035. The draft defines how a SIP User Agent (UA) publishes the detailed
information to a defined collector. RTCP XR measures VoIP call quality such as packet loss,
delay, signal / noise / echo levels, estimated R-factor, and mean opinion score (MOS). RTCP XR
measures these parameters using metrics as listed in the table below. RTCP XR messages
containing key call-quality-related metrics are exchanged periodically (user-defined) between the
device and the SIP UA. This allows an analyzer to monitor these metrics midstream, or a device to
retrieve them through SNMP.
● The RTCP XR feature is available only if the device is installed with a License Key
that includes this feature. For installing a License Key, see License Key.
● If the RTCP XR feature is unavailable (not licensed or disabled), the R-factor VoIP
metrics are not provided in CDRs (CDR fields, Local R Factor and Remote R
Factor) generated by the device. Instead, these CDR fields are sent with the value
127, meaning that information is unavailable.
● While the device attempts to determine the signal level, it reports a MOS value of
“127 (NA)”. Once it has determined the signal level, it reports the estimated MOS.
● Packet loss effects voice quality estimation only during periods of voice. During
periods of silence, packet loss does not effect or degrade voice quality.
You can configure the device to send RTCP XR to a specific IP Group. The device sends RTCP
XR in SIP PUBLISH messages. The PUBLISH message contains the following RTCP XR related
header values:
■ From and To: Telephone extension number of the user
■ Request-URI: IP Group name to where RTCP XR is sent
■ Event: "vq-rtcpxr"
■ Content-Type: "application/vq-rtcpxr"
You can also configure the stage of the call at which you want the device to send RTCP XR:
■ End of the call.
■ Periodically, according to a user-defined interval between consecutive reports.
■ (Gateway Application Only) End of a media segment. A media segment is a change in media,
for example, when the coder is changed or when the caller toggles between two called parties
(using call hold/retrieve). The RTCP XR sent at the end of a media segment contains
information only of that segment. For call hold, the device sends RTCP XR each time the call
is placed on hold and each time it is retrieved. In addition, the Start timestamp in the RTCP XR
indicates the start of the media segment; the End timestamp indicates the time of the last sent
periodic RTCP XR (typically, up to 5 seconds before reported segment ends).
The type of RTCP XR report event (VQReportEvent) supported by the device is VQSessionReport
(SessionReport). The device can include local and remote metrics in the RTCP XR. Local metrics
are generated by the device while remote metrics are provided by the remote endpoint. The
following table lists the supported voice metrics (parameters) published in the RTCP XR.
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