Understanding the MOS Rating Scalelink to this section
MOS is expressed as a single decimal number on a strict 1-to-5 scale. Within reporting applications like Analytics for 8x8 Work, these scores are grouped into standard Voice Quality (VQ) classifications:
| MOS Score Range | Voice Quality (VQ) Score | What the User Experiences |
|---|---|---|
| 4.0 – 5.0 | Excellent | Perfect clarity; indistinguishable from a face-to-face conversation. Perfect data packet alignment. |
| 3.0 – 4.0 | Good | High quality with minor imperfections. Clear communication with minimal ambient distraction. |
| 2.5 – 3.0 | Fair | Noticeable distortion, occasional syllable clipping, or slight echo, but still entirely intelligible. |
| 0.1 – 2.5 | Poor / Very Poor | Severe audio degradation, robotic or heavily scrambled sound, frequent dropouts, and frustrating conversational delays. |
| 0.0 or 127 | N/A | Data unavailable or call leg length insufficient to calculate a precise network score. |
Technical Note: Because standard industry audio codecs (such as G.711) compress audio data packets to optimize internet bandwidth, the practical maximum score for a standard digital VoIP call is roughly 4.4. If your systems show a consistent baseline above 4.0, your network is executing at peak performance.
Utilizing MOS to Troubleshoot System Operationslink to this section
Within cloud communication ecosystems like 8x8 XCaaS, administrators use the Call Quality Dashboard to continuously track MOS distributions over days, weeks, or months to maintain high operational standards:
- Isolate Remote WiFi Degradation: If specific customer service reps show a sudden drop into "Poor" MOS groups, administrators can drill down into the Endpoint Voice Quality report. This isolates whether the dropped packets stem from local network issues (like a remote worker's home WiFi) or corporate ISP routing paths.
- Optimize WAN and SD-WAN Routers: Regular shifts in the corporate Call Quality Trend board warn system architects to review Quality of Service (QoS) rule allocations, ensuring voice traffic maintains absolute priority over bulk background downloads.
