Mean Opinion Score (MOS) is a test used in telephony networks to obtain a human user's perspective of call quality in a particular network. Customers can obtain MOS scores for their networks by visiting: Will my internet connection and network support high quality VoIP calls?

MOS Score Summary Reference: 

1 - Unsatisfactory - Very annoying distortion which is objectionable

2 - Poor - Annoying distortion but not objectionable

3 - Fair - Perceptible distortion that is slightly annoying

4 - Good - Slight perceptible level of distortion but not annoying

5 - Excellent - Imperceptible level of distortion

What Customers should expect: 

A MOS score of 4 is very optimal for a G711 codec call, which is ESI Hosted Services standard codec, and is comparable to Toll quality. A score of 5 is a rare occurrence and not receiving scores in the range of 5 is not a disqualifier for a high quality voice experience with ESI Hosted Services, as well as VoIP in general.

Most ESI Hosted Services customers using BYOB (Bring Your Own Broadband) can expect a rating of 3.3 - 4.2 in non-congested converged networks. Customers with heavily congested networks will see ratings of 1 - 3.1; in those scenarios we highly recommend considering a dedicated internet connection for the phone service, or the implementation of Quality of Service (QoS) on customer networks. For customers seeking the highest quality of voice possible, please contact your ESI Hosted Services representative to discuss internet options which include guaranteed QoS (sometimes referred to as Class of Service or CoS for short). 

• For more information on QoS and MOS, please see our documentation source: Data Network Resource