Using the tel Protocol with 3CXPhone for Windows

What is the tel Protocol?

The easiest way to define what the tel protocol is, is to simply think of it as a link that communicates a telephone number. That means that when you click on a tel link the tel protocol will try to pass the number to an application that can make a call. A tel link takes the form of: tel: +35722444032.

The first part of the URI defines the protocol and the second part defines the number to be dialled (which can be in either local or international format). The 3CXPhone client now integrates with the tel protocol to provide the users with click to call functionality.

Using 3CXPhone with tel Protocol

To start making calls using the tel protocol, install the 3CXPhone for Windows client on your machine, and then follow these steps:
To use click to call functionality first find a web page with Tel Links in this case we will use

  1. Find a web page that has tel links. In this example we will use Click on the tel link.
    After clicking on the Tel links you will receive a request to launch an external application to handle it. Select 'Launch Application' to use 3CXPhone for Windows
  2. A popup will appear with the title “External Protocol Request” asking you to launch the registered application (3CXPhone for Windows) to handle this tel link.
  3. Select “Launch Application” to use 3CXPhone for Windows Client.
    After clicking Launch Application the 3CXPhone for Windows will maximize and dial the number.
  4. 3CXPhone for Windows will maximize and and make the call to the number contained in the tel link.

Associate the tel Protocol with 3CXPhone

3CXPhone for Windows will register as the handler for tel protocol during installation automatically. If you discover that another application has registered to handle the tel links at a later stage you can change that registration back to 3CXPhone:

To restore Tel  protocol handling back to 3CXPhone for Windows open the Windows Control Panel and click on 'Default Programs'

  1. Open the Windows Control Panel and click on “Default Programs“.

    After selecting Default Programs click on 'Associate a file type or protocol with a program' button
  2. Select “Associate a file type or protocol with a program” from the default programs list.

    Scroll down the association list to protocols, click on 'Tel' and press 'Change Program'
  3. Scroll down to the bottom of the list in the protocols section, find TEL, select it and click “Change program“.

    Select 3CXPhone for Windows from the list of programs to set it as the default handler for Tel links
  4. Select “3CXPhone for Windows” from the list of programs. Click on the close button to close the “Set associations” panel.

You have now set 3CXPhone for Windows to be the default handler for tel links.


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  1. Chris

    When following the above “3CX Phone for Windows” doesn’t come up as an option to click.

    It does allow me to browse to find the program on my hard drive. Where should I navigate to and which program on my hard drive should I select please?

    April 25, 2014 at 7:19 pm
    • @Chris – Good question – I am not sure and will need to check for you, however you have 2 possible solutions.
      Either calltriggercmd.exe or 3CXPhoneWindows8.exe. Both are located in program data folder. I think calltriggercmd as that is the EXE that the .tel action needs to call.
      There is an image above that shows the default Google image when an external application is launched – if you scan in there there is a path to a file in program data. That is the path where the 3CX Phone binaries are located.
      If you do not want to experiment with this, contact 3CX Support and they will tell you exactly what to do and possibly remote in to fix this problem.

      April 27, 2014 at 9:35 am
    • Chris

      Hi Nicky, thank you for your reply.

      Reading other posts, I can see two potential problems I have –

      1. We use Office 365 Midsize business subscription, which includes the desktop install of Office 2013 Pro Plus. Lync is part of this and to the best of my knowledge can’t be separately uninstalled.

      2. There is mention in other posts of Pro vs Standard licence of 3cx. We have the standard licence. Will this work or is it a feature of Pro only? The blog post didn’t mention anything about being a Pro only feature.

      April 27, 2014 at 5:57 pm
  2. Craig

    After installing 3cx phone for windows the tel URL registers to calltriggercmd which I think works in pro only.
    I’m on standard.
    When i try to change the program – the only options are calltriggercmd, chrome and lync

    April 25, 2014 at 7:27 pm
    • Hi
      I´m using PRO, but see the same.
      I´m on Win 8.1, and the tel: is relatet to Google Chrome.
      When trying to change, I have the following posibilities: Lync & Skype and Find a app in Windows store. I do not have Lync and Skype installed, so this looks like another Microsoft “yes we do want to harassing the little people” :-(

      April 26, 2014 at 12:02 am
    • Hi..
      A correction, I did have Lync, it was installet together with Office 2013… I removed Lync, but still do not have the posibility to select other than now Skype, or find a app. I´m not able to select 3CX Phone.
      Anoyone knows how we can make 3CX Phone selectable ?

      April 26, 2014 at 12:28 am
    • If you had lync, then lync steals everything permanently. Remove Lync. After that REINSTALL 3CX Phone for windows. When lync is installed it modifies windows to work with it as the only telephony software. (leaves some exceptions for skype but still extremely selfish in it’s work – everything is adjusted for lync). When other software is installed, the software even though the behavior is correct, will not work because lync overrides some undocumented internals that no one seems to know except lync. When lync is removed, the previous software is still ignored and will still not work. All tel software needs to be reinstalled. To avoid confusion, uninstall lync, reinstall Skype and reinstall 3CX Phone in this order.

      April 27, 2014 at 9:29 am
    • Hi Nicky

      Did annyone told you that you are brilliant?
      – in not, then let me be the first :-)

      It worked… After uninstalling Lynch – that was added without my awareness during MSO 2013 installation – I did a uninstall / reinstall of the 3CX Phone, and now I can select 3CX Phone as my standard software to be used with the TEL Protocol.

      Thanks, it is great to get working answers :-)


      April 28, 2014 at 7:02 pm
    • @Craig – following your post and I see you make some progress. Yes this works in PRO Only. So the license has to be PRO. Standard, notifications are disabled. Tel uses heavily calltriggercmd plugin. This is a way to trigger calls from command line. As a result it uses the 3CXPhone API to work and the API is blocked in standard and only a professional feature with the exception of TAPI and Outlook Integration.

      April 27, 2014 at 9:31 am
    • Craig

      If pro only – would be nice for 3cx phone not to create the tel links until a pro license is identified on the server.

      April 28, 2014 at 9:08 pm
  3. Craig

    I found in the registry and manually changed it – but still no dice.

    April 26, 2014 at 12:59 am
    • @craig – Be careful from the registry. the massive amount of changes we needed to add in the registry to make this simple protocol work was impressive… Leave everything as it is, install all software and install 3CX Phone Again and we will check after.

      April 27, 2014 at 9:26 am
    • Craig

      I only made that 1 change. But since tel wi work in pro only my work is done. Except to remove the tel links from others desktops.

      April 28, 2014 at 9:13 pm
  4. I was searching the internet for a long time to find a solution like this.
    I follow the steps as describe in the article above and it work like a charm.
    So easy and so close by.
    Thank you.

    April 27, 2014 at 10:32 am
  5. Neven

    Has anyone solved the problem?
    I using 3CX Phone how can make cals with tellto: protcol with this software?

    May 9, 2014 at 10:59 am