An update to the Asterisk billing software, A2Billing, has been released and is now at version 1.9.2
This update includes an interesting, and much requested feature, they have called a-leg billing. What this allows you to do is bill per minute for the inbound part of a DID/DDI call. This is in addition to charging for the outbound leg of the call (if the call is forwarded to a PSTN number).
There were various (messy!) hacks people used to accomplish this in the past and it’s great to see it included as a core feature.
If you would like to see more information regarding this please visit here – http://www.asterisk2billing.org
Also, if you use A2Billing there is a link on that page where you can donate and assist with the future development of the project.