Jangl has always been about assigning a relationship it's own telephone number. They've recently extended this concept by allowing you to call anyone by simply knowing their email address. Now they're taking it a step further by integrating a PhoneBook into Facebook, which recently opened it's API to new applications.

By adding the PhoneBook application

into Facebook, you can now easily create a telephone number–local to you–that you can use to contact any of your friends on Facebook. When you call that number, you leave them a message, which your contact listens to and will decide whether or not to connect with you. Your real phone number isn't provided at all in this process.