SOFTPHONE TUTORIALS
This is quite a typical authentication challenge when the server considers credentials invalid.
This is usually caused by billing or service restrictions. Click to find out more.
It indicates that the SIP server got and understood the request but refuses fulfil.
The server cannot locate the user, extension, or phone number specified in the request. A set of possible reasons inside.
A proxy server between the SIP client and the telephony server cannot authenticate the request. Valid credentials required.
Typical causes lie in network connectivity issues, firewall blocking, or incorrect credentials. Click to read more.
It shows that a call reached the destination, but the endpoint device is unable to accept at the moment.
This error occurs when a SIP request is sent back to the same server that already processed it, resulting a routing loop.
It indicates a VoIP call was canceled by the caller before it was answered. Click for key causes and troubleshooting.
A media negotiation failure, typically caused by codec mismatches between calling and called parties.
SIP server cannot fulfill a request due to misconfiguration, resource limitations, or some other reasons.
This is typically a server-side issue, often caused by misconfigured SIP trunks, DNS issues, or overloaded servers.
This error indicates a temporary failure where a server cannot process a call due to routing or other issues such as overload or maintenance.
Click to read why it occurs and how to fix.
How to diagnose SIP call issues when no ringback tone and no connection.
Diagnosing SIP issues when users see inbound calls but no connection reached.
Diagnosing SIP issues when there are no inbound calls despite successful registration.
A call connects normally, but one side cannot hear the other. This guide explains how to identify one-way audio issues and troubleshoot them.
A practical guide to diagnosing VoIP call quality problems such as echo, distorted sound, and audio delays.
