Billing for kamailio?

Question

VoIP

It is necessary to fasten billing to kamailio, take money for calls through the server. But I could not find any manual on the topic.
There are a lot of projects: like Siremis, cnxcc module, a2billing, etc. But nowhere is it said how to put it all together to get money.
Prompt please well documented projects for creation of billing. What is the best solution to use? How to connect them with payment systems, without writing bicycles.

Answer 1

fintech open source no
GNU Cash the only exception is
so faster / more reliable - bikes or buy something cheap

Answer 2

I figured out with Siremis. There's only half the billing. You have to write the other half yourself.

Answer 3

There are cgrates, they have quite flexible everything is configured