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Course Content - Advanced

Basic Troubleshooting


Welcome to the online training series from 3CX. This module will take you through the Basic Troubleshooting of 3CX.


There are a variety of tools and resources available to troubleshoot the PBX when an issue arises.

We will see the various bits of information the PBX will provide in order to facilitate the administrator to pinpoint any issue is.


Let’s start with the PBX dashboard. The Dashboard will provide a quick overview of the current activity and status of the PBX. We will be able to see at a glance whether everything is running the way it should.

From the screenshot shown, you will be able to see that the Firewall Check has not passed and it is shown in red, and we also do not have automatic backups. There is nothing better than a current backup to save you when a disaster happens. Always enable automatic backups. Better to be safe than sorry.


By default, the PBX will retain minimal logs, in order to conserve CPU power and disk space.

By default, the PBX will retain minimal logs, in order to conserve CPU power and disk space.

When the services are restarted or the PBX server itself is restarted, the log files will be cleaned to allow you to create a fresh set of logs, when needed.

In order to troubleshoot possible issues with the PBX, the normal logging level of LOW will not be sufficient, and Verbose logs will be needed. By definition, verbose means having more information than what is required, and in this case we will need a lot of information which the PBX is in position to provide us.

The log files of the PBX are retained in a folder on the server itself.

The various log files kept by the PBX are also available for perusal from the management console in addition to being available from the file system of the server. The “Logs” button in the Activity log gives you access to the logs, allowing you to download them onto your computer.


In the Activity Log we are able to see basic SIP Flow messages given by the PBX in relation to phone registrations, interactions with gateways and providers as well as information on the calls being processed by the PBX.

These can be filtered based on the date and time an event happened and we would want to troubleshoot.

If we want to filter by extension, this is also possible, and in addition to that, the relevant calls for that extension will only be visible in the Call drop down box. The call ID is an incremental counter of calls since the PBX or services were last restarted.

An external tool called the 3CX Binary Log viewer allows you to import the log files of the PBX and perform more detailed analytics of the PBX.


The event log can be found in the dashboard and it provides summarised events pertaining to the registrations of Extensions, providers and gateways.

Requests sent to the RPS servers of IP Phone providers are also logged here giving an indication if the requests is successful or not.

IPs being blacklisted are also logged here.

There are 3 different levels shown, warnings, errors and informational messages. These can be filtered and shown as separate, individual levels.


Emails are the main way that the PBX will inform the admin of the activity in the PBX. In the email notifications settings of the PBX more than one admin is possible to be configured. All that is needed is to comma separate these addresses.

This will require a valid and tested SMTP Server to be defined on the PBX.


Another tool in the administrators arsenal, to troubleshoot call issues is the inbuilt packet capture utility, which allows an admin to easily take a packet capture on the PBX, right from within the management console.

You will need to have wireshark installed on a windows machine to have the necessary prerequisites to run the packet capture. In a Linux environment, this is not needed as all the necessary packages are installed upon installation of the PBX.

Choosing the relevant interface, or choose to capture on all the interfaces if the server has more than one interface, just click Capture to start the capture.

When the capture is stopped, a download link will be provided to download the capture, as well as a link to create the 3CX Support information, which will also include the capture in the log files.


The majority of configuration and troubleshooting can be done from within a web browser in 3CX, but there are some cases where access to the operating system is required.

With the 3CX Linux Edition, this would require an SSH client to establish an SSH connection to the operating system.

A connection to the machine is easy to achieve in a Linux environment without the need for an SSH Client. From the dashboard, a button to access the web shell terminal is available. This will give you access to a limited set of functions which may be needed for troubleshooting.

[SLIDE 10]

Using the capture taken from the management console, we can use Wireshark to decode the capture and perform a SIP flow debugging. This is very easy in Wireshark, as VoIP calls can be isolated and analysed in a clear, easy to read format.

All we need to do is select the relevant call legs we want to analyse and click Flow Sequence.

The selected call legs will now be represented in a graphical form, making it easy to see the flow of the call from beginning to end.

[SLIDE 11]

As the packet capture is done from the servers interface, any audio traffic traversing the interface will also be captured.

You will be able to see the different audio streams coming from the SIP endpoints, allowing you to determine where problematic audio is originating from, if you are facing audio issues.

Any timing issues on the packets coming in and leaving the PBX will also be shown in the audio streams.

We will need to select the call legs and click Play Streams.

Ideally 4 audio streams will be seen in a call between 2 SIP endpoints, when the audio is proxied by the PBX. One for each of the streams from the PBX to the end points and one each from the end points to the PBX.

[SLIDE 12]

This is what the wireshark interface looks like. Of particular interest here is the fact that we can use the graphical flow diagram to pick a particular packet, and this will take us directly to the packet itself, with the payload of the packet shown as well.

A more detailed guide on how to capture network traffic can be found at the link shown on screen.

[SLIDE 13]

It isn't always easy to troubleshoot an issue on your own, and sometimes it is necessary to bring in the big guns to assist.

However, before asking for assistance, we would recommend looking at our online documentation, which contains a wealth of information concerning all aspects of the configuration of 3CX.

This ranges from the configuration guides for each model of the supported phones, gateways as well as the prerequisites of the PBX in detail.

Occasionally, when we release a new feature, or when we see that some people are having difficulty with a certain feature, we publish a technical document which will clarify things up for people.

[SLIDE 14]

Now, after you’ve done your research and done your best, you may still be facing difficulty configuring or troubleshooting an issue.

This is where you call in the cavalry, and bring in the big guns, namely, 3CX Technical Support.

Our technical Support team is on hand to provide assistance to our active partners, who are our first line of defence in troubleshooting issues for our customers. Support is also provided to inactive partners and end users, upon purchasing of a support ticket.

Support can be provided for all the supported equipment, which is defined on our technical support website,, as well as supported SIP Trunks.

3CX branded products have support for the latest version as well as the immediate previous version. Currently, versions 15 and 15.5 are supported.

Support is also provided for the 3CX Clients as well as 3CX Webmeeting.

3CX Technical Support can be engaged in one of two ways, either by telephone for our active partners, which is convenient for receiving advice, guidance or clarification of certain issues.

The option to open a ticket, which is the preferred method when the sending of information, for example logs, is required from the customer, or sending of guides and instructions in writing from the Technical Support team.

[SLIDE 15]

Thank you, and goodbye!

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