Billing for Asterisk so far seems to be either open source, with all manner of shortcomings, or thousands of bucks. Is this still the case? Asterisk billing deserves a thread of its own.

Did you manage to find a solution?

What sort of shortcomings are you running into exactly?

http://trac.asterisk2billing.org/cgi-bin/trac.cgi

is a good one

Develop a custom billing module which meets your requirement and integrate it with Asterisk.