
100 Chapter 5 Configuring VoIP trunks
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Quality of Service Monitor
The Quality of Service Monitor is an application that monitors the quality of the IP channels. It
does this by performing a check every 15 seconds. The QoS Monitor determines the quality of the
intranet based on threshold tables for each codec. If the QoS Monitor is enabled, and it determines
that the quality of service falls below the set threshold, it will trigger fallback to PSTN. For
information about setting up the system to use QoS and fallback to PSTN, see “Configuring PSTN
fallback” on page 80.
Bandwidth required for QoS monitor: There are a total of 25 monitoring packets traveling in
each direction every 15 seconds. Each of monitoring packages has 88 bytes in IP layer. These
monitoring packets are equally spaced out in the 15-second interval. For example, if there are two
Business Communications Managers, BCM-A and BCM-B, connected to each other with QoS
Monitoring enabled. In every 15 seconds there are 25 monitoring packages going from BCM-A to
BCM-B and then back to BCM-A. Similarly, the same occurs from BCM-B to BCM-A back to
BCM-B. In other words, in this case the overhead in IP layer caused by these monitoring packets is
about (2x25x88)/15= 293 bytes/second = 2346 bits/second in one direction.
Quality of Service Status
The QoS Status displays the current network quality described as a Mean Opinion Score (MOS)
for each IP destination. A pull-down menu allows the administrator to view the MOS mapping.
The table below shows a sample QoS Monitor.
Table 18 QoS status
Updating the QoS monitor data
To update the table with the most current values:
From the View menu, select Refresh.
IP
QoS
Monitor
G.729 G.711
G.723.1 6.3
kbit/s
G.723.1 5.3
kbit/s
Tx Rx Tx Rx Tx Rx Tx Rx
47.192.5.2 Enabled 4.50 4.50 4.00 4.30 4.75 4.70 4.80 4.90
47.192.5.6 Disabled N/A N/A N/A N/A N/A N/A N/A N/A
Note: For the QoS monitor and PSTN fallback to function, both Business
Communications Managers must list each other as a Remote Gateway and QoS Monitor
must be enabled on both systems.
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