VoIP Cookbook: Mean Opinion Score (MOS)
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To find out how good your voice quality is, you can measure it in terms of Mean Opinion Score (MOS) and R Factor, both of which are the unit measurement derived from the users perception on the voice they hear. MOS can be found at http://www.voiptroubleshooter.com/diagnosis/emodel.html. Below we have provided you with examples of MOS measurements based on a number of Codecs.
| User's opinion | R Factor | MOS Score |
|---|---|---|
| Maximum values obtained by G.711 | 93 | 4.4 |
| Highly satisfactory | 90-100 | 4.3-5.0 |
| Satisfactory | 80-90 | 4.0-4.3 |
| Good | 70-80 | 3.6-4.0 |
| Unasatisfactory | 60-70 | 3.1-3.6 |
| Poor | 50-60 | 2.6-3.1 |
| Not recommended | 0 – 50 | 1.0-2.6 |
MOS Score and R Factor are measured based on users' experience on a communication session
Entering other types of codec and values pertaining to our bandwidth for every codec, we obtained the following MOS and R Factor calculation:
| Codec | Frame | Packet Loss | MOS | R Factor | Kbps |
|---|---|---|---|---|---|
| G.711 | 20ms | 0% | 4.4 | 93 | 80.8 |
| G.723 5kbps | 20ms | 0% | 3.8 | 74 | 16.5 |
| G.723 6kbps | 20ms | 0% | 4.0 | 78 | 17.5 |
| G.729 | 20ms | 0% | 4.1 | 83 | 24.8 |