Asterisk Prepaid Self Service

We have a running installation of Asterisk and we want to develop a prepaid billing(registration) platform for our customers. Billing & self service CRM Module features: User/number registration in(from) our existing mysql database connected to Asterisk(for example: we have 1000 free numbers in the database as a registered user gets(on email) first free + pregenerated password from the same table - "sip_buddies" and so on) User should be able to top-up account using IVR or our Website payment gateway. User shoul be able to see their own CDR records. All this packaged in user-friendly web platform with landing page and standart About/Rates/etc sections.