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:
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).