VoIP: 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

VoIP Quality and Bandwidth Calculator

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


See Also