Voice over IP (VoIP) Mean Opinion Score (MOS) is a measure of the perceived quality of voice communications over internet protocol networks. It’s values range from 1 to 4.4 and is calculated from average latency, jitter and packet loss. The formula used is based on ITU-T Recommendation G.107.

The following guide to MOS values can be used to determine VoIP quality:
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​4.4: Best score possible
​4.3 – 4.4: Users very satisfied
​4.0 – 4.3: Most users satisfied
​3.6 – 4.0: Some users satisfied
​3.1 – 3.6: Many users dissatisfied
​2.6 – 3.1: Nearly all users dissatisfied
​1.0 – 2.6: Not recommended