Implementing VoIP Platform with billing and traffic database.

Looking for expert in implementing the following: 1. Implementing either an Asterisk/FreePBX or any other recommended VoIP platform on a cloud based Linux server(s). 2. Implementing A2Billing or any other GUI enabled billing module on-top of the VoIP platform. 3. Design and deploy a traffic volume cut-off database module on-top of the VoIP platform (Formula will be supplied to Freelancer). 4. The platform must be able to manage multiple unique customers and agents billing and accounts. 5. The platform must be able to handle LCR to multiple VoIP vendors. Successful freelancer may be engaged on a monthly support contract.