We are in a time of remote working and the reliance on network sensitive protocols is quite high for example VoIP end-user will call (not using VoIP) to complain that they have odd issues with there calls dropping and quality being bad.
Below is a very useful table for troubleshooting the cause to optimise your time.
|Most Likely cause
|Dropped packets (errors) / Jitter
|Delay / Echo
|Synthetic Voice (Dalek)
|Jitter / Out of sequence delivery
|Soft / Loud Voice / muffled voice
|Silence / Background Noise
|Voice activity detection (noise gates) / input issue check the MIC
Hope the above helps with common VoIP quality issues.