I was able to solve this problem. These are the necessary settings for Skype Primary:
Under VoIP Configuration:
For Service Provider, select " Skype Primary" if available, then click " Update Configuration" . Otherwise, select " Manual Configuration" .
The only box that should be checked is " Disable public IP address substitution"
In the VoIP Provider section:
Both server names should be " sip.skype.com"
Outbound proxy should be blank.
Realm/domain must be " sip.skype.com"
Under VoIP Numbers:
Select the VoIP Profile: " Skype Primary"
Under Phone Number, enter the entire " SIP User" number from Skype.
Enter the same " SIP User" number in the " User/Account" field.
Enter the password from Skype in the " Password" field.
You may need to save the configuration, but the registration should work for you at this point. (You will still need to setup a hunt group to place calls.)