[Asterisk-Users] CDRs and billing

[Joao Pereira]

Hello
I configured Asterisk to put CDRs in the database like it was explained in:
  www.voip-info.org/wiki/view/Asterisk+cdr+pgsql

What I want to know is how do the billing solutions (like 
Asterisk2Billing) work with Asterisk.

The billing system just use the information that Asterisk puts in the 
CDR table?
Or they connect directly to Asterisk?
Or is Asterisk that has, before the Dial command, to put the information 
on the Asterisk2Billing tables?

Thanks
Joao Pereira