Why am I getting the Windows Firewall warning on Skype Meetings App?

You are getting the Windows Firewall warning on Skype Meetings App, because Windows is trying to protect you from any programs communicating to external systems using special protocol used by Skype Meetings App.

When you use Skype meeting URL like, https://meet.lync.com/xxx/yyy/zzz?sl=1 or https://meet.lync.com/xxx/yyy/zzz, in a Web browser, you will be prompted to confirm to run Skype Meeting App for URL:sfb or URL:lync15 protocol links. "xxx", "yyy" and "zzz" will be your organization name, the meeting organizer ID and the meeting ID.

Click "Open URL:sfb" or "Open URL:lync15 Protocol" to confirm. You may see the following Windows Firewall warning:

Windows Firewall has blocked some features of Sky Meetings App 
on all public, private and domain networks.

Allow Skype Meetings App to communicate on these networks:
[x] Private networks, such as my home or work network.

Click "Allow access" to let Skype Meetings App to run.

The picture below shows you the Firewall Warning on Skype Meetings App::

⇒ Skype Meetings App Functionalities

⇐ URL:sfb and URL:lync15 Protocols

⇑ Skype Web App on Windows

⇑⇑ Skype - Frequently Asked Questions