You must have observed that email addresses and phone numbers available on a webpage are clickable. Clicking on an email address launches the default email handler program (e.g. Outlook, Gmail) on mobile phone or desktop. Similarly clicking on a phone number will launch the dialer if clicked from a mobile device. This helps in increasing user engagement.
Same way Skype URI can be used to initiate a Skype Call or instant message from web pages and spreadsheets. However this will work only if the Skype client is installed in user's device (Smartphone or Desktop). These features can be easily embedded in Excel or Google Spreadsheets.
How to Insert Skype Link in Offline Excel Sheets
In offline Excel files you can use the standard Skype URI to integrate Chat and Call feature from within the sheet. Use this formula to add a hyperlink. username highlighted in red should be replaced with the real username.
=HYPERLINK("skype:username?call","Click to Call")
=HYPERLINK("Sskype:username?chat","Click to Chat")
Below Example gives a formula to add the link dynamically in multiple rows.
How to Insert Skype Link in Online Google Sheets
Skype URI can not be added directly in Google sheets as they do not support any protocol other than regular http and mailto protocols.
As a simple workaround, you can prepend the below link before username and it will launch the Skype App when clicked.
=HYPERLINK("https://saveas.org/skype/call/username","Click to Call")
=HYPERLINK("https://saveas.org/skype/chat/username","Click to Chat")
See in Action - http://bit.ly/SkypeHyperlink