Reports for Monitoring › Interpreting Data in Reports › Units of Observation › Call Quality Observations

Call Quality Observations

The call minute is the unit of observation for most call quality metrics. Each call quality metric is a weighted average over the number of call minutes for each call that ends during the five-minute reporting interval. Normal rounding of seconds into minutes is also performed. For call quality metrics, each call leg contributes its metrics separately.

The following example clarifies the relationship between observation units and call quality metric calculation. Assume that two calls were made from A to B during a five-minute reporting interval: one call of nearly 2 minutes, and one call of approximately 3 minutes. For the MOS metric, the following data was gathered:

The calculation for MOS is a weighted MOS for the five-minute reporting interval that uses the actual total duration of calls in seconds. Totals for seconds are rounded to derive the totals for call minutes.

The MOS calculation is:

(116*3.1) + (182*3.8) = 1051.2
1051.2/300 seconds = 3.50

In this example, the MOS is 3.50 for the reporting interval and is rated as Excessive, using the default thresholds. The number of call minutes reported is 5.