---
title: "VoIP Diagnostics FAQ"
slug: "voip-diagnostics-faq"
updated: 2025-12-09T11:59:43Z
published: 2025-12-09T11:59:43Z
canonical: "docs.uboss.com/voip-diagnostics-faq"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://docs.uboss.com/llms.txt
> Use this file to discover all available pages before exploring further.

# VoIP Diagnostics FAQ

#### How is a Mean Opinion Score (MOS) calculated?

Probes monitor the voice traffic and record several measures for each media stream.

- The number of lost packets.
- The variance of delays between the received packets (jitter).
- The distribution of lost packets inside the stream.
- The codec used.

Based on these values, VoIP Diagnostics will estimate the MOS.

#### What are the MOS thresholds?

Very satisfied = over 4.33 Satisfied = 4.03 to 4.33 Some users dissatisfied = 3.60 to 4.02 Many users dissatisfied = 3.10 to 3.59 Nearly all users dissatisfied = under 3.10

#### What are the common registration status codes?

200 = Successful registration. 401 = Device failed to answer the authentication challenge. Check for SIP ALG. 403 = SIP password does not match. Restart the supported device to load a new configuration. 404 = User does not exist. Check the provisioning of the user and device.

#### What are the most common call status codes?

200 = Successful call. 480 = Unable to reach remote party. 486 = Call has been rejected on a specific device. 487 = Caller has terminated the call before the remote party has answered. 603 = Call has been rejected by the user.