MPC Free 188.8.131.52
With My Private Contacts you will have a password protected phone list.
You can make calls from the app, and they will appear like "MPC" in the call log.
Remember to delete those call logs and to change the default password!!!
The Free version has Ads and the contact list is limited to two contacts. You can purchase the PRO version in the MarketPlace
Requirements: Windows Phone 8.1, Windows Phone 8, Windows Phone 7.5