Everyone - Click-to-Call Not Working in Excel or Microsoft 365 Apps

In some Microsoft applications, particularly Microsoft Excel and other Microsoft 365 desktop products, tel: hyperlinks may fail with an error stating "Cannot open the specified file", even though dialing works correctly elsewhere in Windows. Using the tel:// format resolves this issue and allows calls to launch successfully in supported phone applications.

Purpose

This article explains why tel:// hyperlinks should be used instead of tel: when creating click-to-call links in certain supported applications, such as Microsoft Excel and other Microsoft 365 desktop apps. This guidance ensures consistent click-to-call behavior and avoids common errors encountered with tel: links.

Process

Issue Overview

Users may encounter the following behavior:

• Clicking a tel: hyperlink in Excel displays an error stating the file cannot be opened.
• Entering the same tel: link manually using the Windows Run dialog works correctly.
• The phone application (for example, Cisco Jabber or Microsoft Teams) is installed and functioning as expected.

This occurs because some Microsoft 365 desktop applications do not reliably pass tel: links to Windows, even when the operating system is correctly configured.

 

Supported Solution

Use the tel:// format instead of tel: when creating clickable phone links.

Example:

tel://812084779817

Windows treats tel: and tel:// equivalently, but Microsoft 365 applications allow tel:// links to pass through correctly. This enables the phone application to open and initiate the call as expected.

 

Example in Microsoft Excel

When creating a hyperlink in Excel, use the following approach:

• Hyperlink address:

tel://812084779817

This format prevents the "Cannot open the specified file" error and supports seamless click-to-call functionality.

 

Supported Applications

The tel:// format has been verified to work reliably in:

• Microsoft Excel (Desktop)
• Microsoft Word (Desktop)
• Microsoft PowerPoint (Desktop)
• Windows File Explorer and Run dialog

Web browsers and other non-Office applications typically accept both formats.

 

Notes and Best Practices

• Ensure a phone application is installed and set as the default calling app in Windows.
• Avoid using tel: alone when building workflows that rely on Microsoft 365 desktop applications.
• This guidance applies regardless of the phone platform in use (Cisco Jabber, Microsoft Teams Phone, or other supported calling solutions).