DID management WHMCS - A2bbiling

I use A2billing for call termination/origination billing, I also use WHMCS for all the customer billing. I need a module in WHMCS to manage, provision, and bill clients for the DID's, the module will also have a panel so clients can purchase a DID, when a customer is buying a did it will see a drop down menu to select the country and the it will show the price for the DID. The module has to be integrated with [login to view URL] API so it can get available DID list and can also get the prices. I want to have a option were I can add a percent to the selling price for my profit. Must know about WHMCS and A2BILLING, must be able to provide all documentation detailling changes made in case we need to update a2billing