Snom phone - No events from phone

Description of Problem

Some types of network problem mean that your Snom phone cannot communicate with your PC. This creates problems including:

Usually the problem is that there is a firewall running on the PC, stopping the phone from communicating with the Flexor Manager software. This article will help you identify the problem so that you can correct the configuration of your firewall software. In some cases this is is a result of a security setting on the Snom phone itself.



Note that the problem relates to connections from your Phone to your PC; not the other direction which is from your PC to your Phone. The steps described in this article are as follows:

  1. Check that the hidden tags security feature is turned off on the Snom phone.
  2. Check you can still get access to your Phone from your PC - this direction usually always works.
  3. Check that you are running the Flexor Manager, and that you have a Snom phone added to your system.
  4. Try to connect to your PC from another PC (instead of using the phone).
  5. Identify whether or not your firewall needs a configuration change.
  6. Check to see if you have multiple live network connections with IP addresses e.g. a WiFi LAN connection and an Ethernet LAN connection.

Check Hidden Tags security feature is off

First check that the Hidden Tags security option on the Snom phone is set to off. You can do this by navigating to the Snom phone's web page and selecting the Advanced Settings page followed by the QoS/Security tab. 

If you cannot see the option Use hidden tags then it will not be causing your problem.

If you can see the option Use hidden tags then please ensure that it is set to Off.

For more information on these settings please see the Snom FAQ and our Security Settings FAQ.

Check the Phone can be accessed from your PC

Secondly you should check that you can correctly access your Phone from your PC. The easiest way to do this is to view the web page of your phone; and in doing so, show that the network connection must be working. There are two ways to do this:

If you can get to the web page of your phone, then the Flexor Manager can access your phone, and you should proceed to the next step below. If you cannot access the web page of the phone, then you have a more fundamental networking problem that you should resolve first, and it is unrelated to the Camrivox software. There are many potential causes of this problem, but the discussion of them is beyond the scope of this article.

Check that you are running the Flexor Manager

Before you test the connection to the Flexor Manager software, you need to ensure that it is running (the Flexor icon is shown on your desktop in the system tray area). You also need to ensure that it knows about your Snom phone. The easiest way to check this is by going to the Applications and Devices window and checking that your phone is shown in the window.

Try to connect to your PC from another PC

You have established that the PC can communicate with your phone. Now you need to test the other direction.

What you need to establish is that incoming connections from any device on your LAN can make it to the Flexor Manager software on your PC. The phone is not a special case. This means that you can try to connect to the Flexor Manager using another PC on your LAN. Using another PC is easier than using the phone for this test. The following diagram shows the situation:

Network diagram

Network diagram showing the use of a Test PC instead of the VoIP phone

To test the connection to your PC you need to enter a special URL into the web browser of another PC on your LAN. So you need to have the use of two PCs, your own PC, and another one for helping with the test. The URL uses the IP address of your PC. So you need to begin by finding out your IP address. The easiest way to do this is to look on the Snom phone. The Flexor Manager tells the Snom phone its IP address, so you can ask the phone what it has been told by the PC.

Go to the Action URL Settings page of your phone as highlighted below, and read off one of the Action URLs, also highlighted below:

Action URL web page

Example action URL web page

In the example above the URL you want is, but remember that your IP address will be different and will not likely be; and you need to include the :4052/ at the end. Enter your URL in to your test PC (not the PC running the Flexor Manager), and you should see one of the following messages:

<register code='UNKNOWN' response='error'/>



If you see one of the messages as shown above then you do not have a firewall problem. You must see the message from your test PC.

Note: you will always see the message if you try the experiment on the PC running the Flexor Manager, and it is therefore not a useful test; you must use your test PC to connect to the PC running Flexor instead.

If you do see the message then your firewall is not the cause of your problems, and you should contact support for further help. If you do not see the message, please refer to the next section below.

Firewall problems identified

You have identified that other devices cannot access the Flexor Manager application. There could be a number of reasons for this, but the most likely is that the Firewall on your Windows PC is blocking connections. Windows comes with a built-in firewall but you may also have installed third-party firewall software on your PC. You could even have more than one installed at the same time. Or you may have a router on your LAN that is blocking traffic between different segments.

You need to go to your firewall settings and make sure that TCP port 4052 is open to the Flexor Manager application. In some instances, depending on your firewall, ICMP (Ping) may also need to be explicitly allowed.

Once you have done this, you can retest the connection by repeating the steps above.

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