instructor-learner language learning management site, based on asterisk

We are planning to launch an instructor-learner language learning management site, based on asterisk and skype-like voip system. The site could use lots of [login to view URL] modules, youtube videos, plus charge per text/audio/video chat, VOIP & SMS applications. We need a robust, proven and in-use system that has been working with thousands of users, supporting high traffic, multilingual sites and co-location host. The coding must be simply, neat and clean, support and compatible with ASTERISK, WIKI, RSS. The design/layout must be content-management enabled, and should easily changed by non-programming personnel. The system should be robust enough for easy and cost effective development for the future. The instructors (skilled workers) are paid by talk time via skype while the learners (qualified, pre-selected customers) are charged by their talk time. A learner could be given an asterisk extension after clearing the payment to listen and/or talk; could be blocked to listen and/or talk, after the credit is below certain amount. Using Asterisk working with asterisk2billing, will dramatically reduce your workload on time-billing part. If you have been working on social network systems, please send your reference or demo. Experiences with Asterisk, Drupal etc. would be an asset. IF you would plan to change your bid price after winning the bid, DO NOT BID! SAVE TIME!