Knowledge Base

Phone links in email signatures are not recognized by mobile devices


You use CodeTwo software to add click-to-call links with the sender's phone number to email signatures. These links are not recognized by your recipients' mobile devices: tapping the links does not launch any application.


CodeTwo programs feature several AD attribute placeholders that allow you to have click-to-call links inserted automatically to emails in your organization. Placeholders such as {Phone as link} or {Mobile as link} are filled with the sender's phone number from Active Directory when a message is sent. Typically, when the recipient clicks or taps a phone link, this opens an app that allows the user to make a call or initiate another form of contact. Depending on the mail client and device used to view the message, a phone link can trigger a dialer, a contacts app, Skype, etc.

If some of your recipients view emails on mobile devices, the phone links might not always work. {Phone as link} and similar placeholders in CodeTwo programs use the callto: scheme in the HTML <a> element. The callto: scheme is supported by most desktop applications, but it's sometimes not recognized by mobile devices.

To improve the usability of click-to-call links on mobile devices, you can replace the callto: scheme in your email signature with the tel: scheme (which is also supported by most desktop applications). To do so, follow the guidelines below.

  1. In your CodeTwo software, open (edit) the email signature template that includes a phone link.
  2. Change the scheme in your phone link to tel:. There are two ways to do that:
    • Find the phone link you would like to modify, right-click it and choose Edit link. In the URL address field, change the callto: part to tel: (Fig. 1.).

      Changing the phone link's scheme.
      Fig. 1. Changing the phone link's scheme.

    • Or click the </> Source button on the ribbon to open the HTML source code view. Find the anchor (<a>) element with your phone link and change the callto: part to tel: (Fig. 2.). Click Apply & Close to close the HTML source code view.

      Changed instances of the phone link's scheme in the HTML source code view.
      Fig. 2. Changed instances of the phone link's scheme in the HTML source code view.

  3. Save the changes in the editor by clicking Apply & Close again and then save the signature template in your CodeTwo program. You might need to wait a while for the changes to propagate. Phone links in your email signatures should now be identified correctly by mobile devices. If necessary, you can always revert the changes.
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