Develop Facebook Application

We're looking for a developer who can build and design a facebook application for our products. We have an API for our products which is currently used by our mobile apps and website. We want the facebook app to also interact with this API. The product allows you to make phone calls while recording the call as well as other features. The facebook app needs to display their friends and have the ability to call them. The user will need to have some credits on their account in order to make calls and they can add these credits via credit card or paypal. It would be nice to actually have them add these credits via the new facebook payment system. Once the call is made, it is logged within the app and they can share the recording and post it on their wall.