QX5
QXFXO4/QXISDN4/QXE1T1/QXFXS24; (SW Version 6.0.x) 110
QXFXO4/QXISDN4/QXE1T1/QXFXS24 Manual II: Administrator’s Guide
RTP Statistics
RTP Statistics
page provides detailed information about the
established call is provided. When QX gateway serves as an RTP
proxy, this page displays two groups (legs) of RTP statistics. For
example, when calling from an IP Phone attached to the QX
gateway’s IP line to an external SIP destination or from one external
SIP destination to another through the QX gateway’s Auto
Attendant. Each group of parameters describes characteristics of a
piece of RTP stream composing an overall SIP session. Normally,
one leg describes the RTP stream from caller to the QX gateway and
the other leg describes the RTP stream from QX gateway to the
destination.
Quality - estimated call quality, which depends on RTP statistic.
Below is the legend for Call Quality definitions on the displayed RTP
Statistics:
excellent – RX Lost Packets < 1% & RX Jitter < 20
good - RX Lost Packets < 5% & RX Jitter < 80
satisfactory - RX Lost Packets < 10% & RX Jitter < 150
bad - RX Lost Packets < 20% & RX Jitter < 200
very bad - RX Lost Packets > 20% or RX Jitter > 200
Fig.II- 169: RTP Statistics page
The Local and Remote fields indicate the two peers between which the RTP stream is transmitted. The characteristics in the table below describes to the
piece of RTP stream between these peers.
Rx/Tx Codec - codec for received and transmitted RTP stream respectively.
Rx/Tx Packets - number of RTP packets received and transmitted respectively.
Rx/Tx Packet Size - size of RTP packet (payload) received and transmitted respectively.
Rx Lost Packets - number of lost RTP packets for received stream.
Rx Jitter - inter-arrival jitter is an estimate of the statistical variance of the RTP data packet inter-arrival time, measured in timestamp units.
The inter-arrival jitter is defined to be the mean deviation (smoothed absolute value) of the difference D in packet spacing at the receiver compared to the
sender for a pair of packets. If Si is the RTP timestamp from packet i, and Ri is the time of arrival in RTP timestamp units for packet i, then for two packets i
and j, D may be expressed as:
D(i,j) = (Rj - Ri) - (Sj - Si) = (Rj - Sj) - (Ri - Si)
J(i) = J(i-1) + (|D(i-1,i)| - J(i-1))/16, where J(i) is Rx Jitter for packet i.
For more details about Jitter calculations, please refer to the RFC1889.
Rx Maximum Delay - maximum variance (absolute value) of actual arrival time of the RTP data packet compared to estimated arrival time, measured in
milliseconds.
If Si is the RTP timestamp from packet i, and Ri is the time of arrival in RTP timestamp units for packet i, then variance for packet i may be expressed as
following: V(i) = |(Ri - R1) - (Si - S1)| = |(Ri - Si) - (R1 - S1)|
Rx Maximum Delay = max V(i) / 8
RX Delay Increase Count – indicates the number of times the delay in jitter buffer is increased during the call.
RX Delay Decrease Count - indicates the number of times the delay in jitter buffer is decreased during the call.
Please Note: RTP Statistics is logged only when at least one of the call endpoints is located on the QX. For example, it will not be logged when:
• calls incoming from or addressed to the IP lines or remote extension,
• calls from an external user are routed to another external user through QX gateway’s routing rules.
In the first case, RTP statistics will be logged if remote extension or IP line user is calling locally to the QX gateway’s extension or auto attendant.
The Configure Call Quality Event Notification link leads to the
Call Quality Notification page where call quality control notification specifics can be
configured.
The Configure System Events link leads to the Event Settings page where the methods of notification for each system event can be configured.
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