What is A2Billing?

A2Billing (http://www.asterisk2billing.org/) is open source VoIP billing software (open source simply means that the original source code for the software application is made freely available and may be redistributed and modified).  A2Billing is similar in function to ASTPP.

A2Billing provides a freely available billing solution for VoIP gateways and softswitches.  Common features provided are pre-paid and post-paid billing, call rating, credit control, calling cards management, least cost routing (LCR), did management, resellers management, and more.