prepaid Telephone Software

I need a prepaid telephone system. This system works in the following ways 1. Someone buys a card with numbers and goes to the booth. The he will dial his code and will be able to call for the duration his credit will alow him or her. 2. if the credit on the card is finished then it should disconnect. 3. The credit on the card should be refillable. 4. This means the hardware in the booth is connected to the a database at the counter. The system should be able to support more than 100 users. 5. We have coded telephone system and if you need any help we may supply you with codes. ## Deliverables The work should be fully functional and codes comented and bug free and it should be copy righted to us. ## Platform The system should support all microsoft windows platforms. We might test it on linux in the future.