Configuring Quality Of Experience Profiles - AudioCodes Mediant 1000B User Manual

User's Manual
16.2

Configuring Quality of Experience Profiles

The Quality of Experience feature lets you monitor the quality of voice calls traversing the
device in your network. Voice-metric monitoring profiles (Quality of Experience Profiles)
can be configured and applied to specific network links, including IP Groups (see
'Configuring IP Groups' on page 336), Media Realms (see 'Configuring Media Realms' on
page 313), and Remote Media Subnets (see 'Configuring Remote Media Subnets' on page
316).
The monitored voice metrics include the following:

Mean Opinion Score (MOS): MOS is the average grade on a quality scale,
expressed as a single number in the range of 1 to 5, where 1 is the lowest audio
quality and 5 the highest audio quality.

Delay (or latency): Time it takes for information to travel from source to destination
(round-trip time).

Packet Loss: Lost packets are RTP packets that are not received by the voice
endpoint. Packet loss can result in choppy voice transmission.

Jitter: Jitter can result from uneven delays between received voice packets. To space
evenly, the device's jitter buffer adds delay. The higher the measurement, the greater
the impact of the jitter buffer's delay on audio quality.

Residual Echo Return Loss (RERL): An echo is a reflection of sound arriving at the
listener at some time after the sound was initiated (often by the listener). Echo is
typically caused by delay.
At any given time during a call, a voice metric can be in one of the following color-coded
quality states:

Green: Indicates good call quality

Yellow: Indicates medium call quality

Red: Indicates poor call quality
Quality of Experience Profiles let you configure quality thresholds per monitored voice
metric. These are based on the following color-coded quality thresholds:

Green-Yellow threshold: Lower threshold that indicates changes from Green to
Yellow or vice versa when the threshold is crossed.

Yellow-Red threshold: Higher threshold that indicates changes from Yellow to Red
or vice versa when the threshold is crossed.
Hysteresis is also used to configure the threshold. This defines the amount of fluctuation
from a threshold in order for the threshold to be considered as crossed (i.e., change in
color state). Hysteresis is used to avoid false reports being sent by the device.
Each time a configured voice metric threshold is crossed (i.e., color changes), the device
can do the following, depending on configuration:

Report the change in the measured metrics to AudioCodes' Session Experience
Manager (SEM) server. The SEM displays this call quality status for the associated
SEM link (IP Group, Media Realm, or Remote Media Subnet). For configuring the
SEM server's address, see 'Configuring the SEM Server' on page 301.

Determine access control and media enhancements based on measured metrics.
Depending on the crossed threshold type, you can configure the device to accept or
reject calls, or use an alternative IP Profile for the IP Group to which the call belongs.
For more information, see 'Configuring Media Enhancement Profiles' on page 309.

Alternative routing based on measured metrics. If a call is rejected because of a
crossed threshold, the device generates a SIP 806 response. You can configure this
SIP response code as a reason for alternative routing (see 'Configuring SIP Response
Codes for Alternative Routing Reasons' on page 655).
Version 7.0 303 Mediant 1000B Gateway and E- SBC
16. Quality of Experience