Kamailio/Billing system

First Milestone: ($250) Install Kamailio with Nat Support. Route inbound and outbound calls from the carrier. Second Milestone: ($250)Billing/Ability to rate inbound and outbound calls. Customer account must be able to have multiple sip username and or IP address. Customer's balance will have the cost of the calls deducted and shutoff once the balance goes to or below zero. Web management interface for setting up and managing new accounts. Third Milestone: ($250) Customer interface. Web Portal for users to login and view/edit the following information. 1. Account Balance 2. Customer Information (name, address, phone number, billing contact info) 3. View Call Records. 4. Manage their DIDs ( route dids to sip users, or to local phone numbers (forwarding), or ip address ) 5. view sip user information (username/password). 6. Account Payments History [login to view URL] payment via Paypal.