When making calls in Skype to those who are not in the Contacts list, it is a good idea to hide your own IP address to avoid potential trouble. This is because there are third party services which can resolve your Skype name to your IP address.
Skype has an option regarding this. To enable :
Go to Tools >Options
Then scroll down to Advanced > Connection.
Enable the tick mark next to “Allow direct connections to your contacts only”.
This will ensure that when interacting with non-contacts, your IP address can’t be obtained by third party Skype resolvers. There will be a slight delay when making calls to non-contacts but is well worth the security it provides.