Skype for Business – Must Change Settings
You’ll need to make a few changes in your Skype for Business application on your PC in order to be able to use it.
Press the windows key on your keyboard and type: Skype for Business. Press “Enter” to open it. (Note that Skype for Business is different from Skype. Skype for Business is more of an instant message system within an organization whereas Skype is used for long distance video conferencing.)
Once Skype for Business opens click on the “gear” icon (not the down arrow) to open your preferences.
Select the “Personal” category and then click the “Advanced” button.
Select the “Manual” radio button and type in the following :
Click “OK” and you should be able to use Lync!