Prepaid mobile network in France with no expiry on the credit. BINGO!
Dad's orange unlimited landline / mobiles in France package details, includes many more countries than the free.fr deal.
Similar to Twilio, send / receive voice & sms via APIs. Doesn't appear to be as quickly evolving as twilio, but free for development use.
An open source PBX based on Linux used as a building block in most voice on linux systems.
The commercial arm of a2billing, offering installation, support, and hosting.
a2billing is built on top of Asterisk and handles all kinds of billing requirements. Prepaid calling cards, post-paid, CLI authenticated, etc, etc. Very powerful. Commercial support available.