Phone links in email signatures do not open on mobile devices

You add clickable links to the sender’s Active Directory (AD) field in the email signature containing telephone numbers. These links fail to open when your recipient clicks the link on a mobile device.


The phone links in the email signature may fail to open on a mobile device when they contain a callto: extension.

Sigsync has several AD attribute placeholders for phone numbers such as 'telephoneNumber', 'mobilePhone', 'businessPhones' that enable you to add clickable links in the email signatures. The values for these placeholders are retrieved from the AD and when your recipient clicks on the link, it opens a supported application on their device that allows them to directly make a call or save the telephone number to their contacts.

To enable your recipients to open the telephone links in email signatures, replace the callto: in the Href field of the AD attribute with tel: in the Sigsync editor.

The following steps show how to change the Href in Sigsync for the phone number field.

  1. Click on the phone number field in the signature template

    For instance, click on the 'businessPhones' field if you want to change the hyperlink for the business phone number.

    Click on the phone number field

  2. Under Hyperlink, change the Href property of the businessPhones

    In the properties panel to the right, change the callto: extension in Href to tel: as shown in the screenshot.

    Change the Href property

    Change the callto extension in Href to tel

  3. Click the 'Save link' button to save the changes

    Repeat the preceding steps if you want to change the link for 'mobilePhone' and 'telephoneNumber'. Send a test mail to yourself and verify if you are able to open the links by clicking the phone number field in the email signature.

    Tip: If you want the phone number to go directly to the extension when your recipient clicks on it, change the Href by including the 'customAttribute' field next to the 'businessPhones' as shown.


    Ensure that the 'customAttribute1' field contains the value of the telephone extension for the AD user.

    See steps to set custom attribute in Office 365 and Sigsync

    Save the changes

    After you set the custom attribute, the extension for the phone number is displayed in the Sigsync signature preview window.

    Extension is displayed in the Sigsync signature preview

Streamline Email Signature Management with a Free On-demand Demo from Sigsync

Sigsync email signature service provides effortless, centralized signature management for Office 365 and Exchange. Our team can assist you in quickly setting up company-wide signatures. Request a free on-demand demo to see how Sigsync can simplify your email signature management process.


Demo sitemap