I have a task to make our own virtual PBX for automated attendant and SIP clients.
Scenario is following: We have our SIP account given from our voice carrier now I want to share these lines with other of our branches outside of our LAN network. I want also to be able when someone calls our public numbers to get the automated attendant and be able to call someone in our private PBX network (other SIP clients ).
Now I am looking for some good software for PBX. I'll be most happy with some preinitialized distribution of some system.
Temporarily, I testing pfSense with port of FreeSWITCH. I also know about Asterisk, but there is lot of work to implement this solution. So I am asking you for a recommendation if there is some box which is already tested, reliable and if it is possible free.