The goal of the project would be to have a working configuration of opensips for unlimited talking and asterisk for voice mail. The platform will be debian, media proxy will be used for far end transversal
* Database design.
* System design
* Implementation of NAT transversal, asterisk+opensips voicemail, (opensips to PSTN, well for this we will use a sip termination trunk, with multiple providers, nothing much to think about).
* Configure a2billing to generate Cards with 6 Digit & incremental manner
* Configure a2billing to have prepaid accounts & payment using Paypal.
* Modify Asterisk source code to have Voicemail as MP3 attachment (no need for that now).