MOS (Mean Opinion Score) information is stored for your network for 90 days. This allows you to evaluate VoIP phone calls completed on the network and display a MOS rating for all calls. In multimedia (audio, voice telephony, or video), especially when codecs are used to compress the bandwidth requirement, the MOS provides a numerical indication of the perceived quality from the user's perspective of received media after compression and/or transmission. The MOS is expressed as a single number in the range of 1 to 5, where 1 is lowest perceived audio quality and 5 is the highest perceived audio quality measurement. Expected MOS ratings should range between 4.0 - 5.0, indicating a high quality phone call. Our alerting system is set to trigger an alert when audio quality drops below a 4.2. On the MOS History screen, you will see several pieces of information starting with a past week graph and a past 90 days graph. Below these graphs, you will find a chart listing several important pieces of information when it comes to diagnosing VoIP calls: Call Date, Duration, Caller, Who Called, Who Ended the Call, Source of Call, Destination of Call, Domain, MOS SCORE, BYE, and Max Jitter in milliseconds. As with our other charts, you are able to export this chart to an Excel Spreadsheet or a PDF.