Hello,
From your description, you want the inbound calls to be received on your freepbx server, then transferred to bitrix24 to be handled by the available agents there. The key to every successful inbound campaign is how this is done, so based on your campaign nature, we will also put in place some IVR, working hours, background music when the calls are on hold, probably several ingroups to filter the calls based on a given criteria, all this so that the transfer can be smooth and you don't lose customers in the process.
outbound calls will be easy to set up of course.
I will be waiting for your message so that you can enlighten me more with specific details.
best regards.