You can control who contacts you on Skype by changing your privacy settings. To avoid nuisance calls and unwanted instant messages, you can choose to only allow those in your contact list to contact you, and you can block and report any nuisance contacts.

To only allow people in your contact list to call you or send you instant messages:

1. Sign in to Skype.
2. In the menu bar, click Skype > Preferences... and then click Privacy.
3. In the section Allow calls from, select Contacts.
4. In the section Allow messages from, select Contacts.

To block and report a nuisance contact:

1. In the sidebar, right-click the person you wish to block and select Block [name of contact]… A message box displays prompting ‘Are you sure you want to block [name]?’
2. Tick Report abuse from this person to help Skype block abusers and spammers in the early phase of their activities.
3. Click Block.