# Glossary: Mean Opinion Score (MOS)

### TelcoBridges and MOS

Toolpack uses a well-known model to evaluate a MOS value based on collected statistics for a call. There are 3 factors that significantly impact the call quality: latency, packet loss and jitter of RTP packets. Using these statistics, we calculate an R-value that ranges from 1 to 100 where a higher number is better. Finally the MOS is calculated using this formula.

\
MOS = 1 + 0.035R + ((R - 60) \* (100 – R) \* 0.000007R)

#### TelcoBridges' MOS Implementation

For the MOS calculated from the R-value, there is no notion of codec. We decided to apply a ratio in relation to the codec's ideal MOS.

See the table below:

<figure><img src="https://docs.telcobridges.com/w/images/f/fb/Mos_codec_conversion.jpg" alt="" width="563"><figcaption></figcaption></figure>

**Network quality**

TelcoBridges' MOS implementation adds another concept over the standard MOS: Network quality. The network quality parameter provides a fast way to identify a bad network condition. The MOS is useful when comparing calls for the same [NAP](/appendices/appendix-a-glossary/glossary-nap.md) or for the same network. But if you are using several codecs, the MOS value might be misleading to detect network problems.

<br>

* Examples:
  * A perfect network (i.e. no packet loss, no latency) using G.723 will have a MOS of 3.6. This is relatively low, but it represents a network quality of 100%. The only way to improve the MOS will be to use a higher quality codec.
  * On the other hand, a G.711 call with a MOS of 3.7 represents a network quality of 86%. This rather low and based on these values, you know there is something that can be improved in the network.

<br>

**Ingress-Egress**

There are 2 MOS values calculated per call leg. The ingress value is using RTP reception statistics and the egress value is using RTCP statistics received from the peer. Using these statistics, w can calculate MOS and network quality for the ingress and egress directions.

When using Call Trace, the lowest value between ingress and egress MOS and network quality are displayed.

### Related subject

* [MOS scores in CDRs](/configuration-details/configuration-by-web-portal-category/call-detail-records-cdr/radius-cdrs/radius-cdr-attributes.md)
  * [Statistics in the CDRs](/configuration-details/configuration-by-web-portal-category/call-detail-records-cdr/cdr-variables/call-statistics-available-in-cdr.md)
* [MOS in routing scripts](https://docs.telcobridges.com/wiki/Routing_script_tutorial:Mini_Development_Guide#Script_parameters_protocol_mapping)


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