Install free pbx on public ip

Dear Friends,
As I am new to free pbx , I want to inquire if I will install free pbx on public ip,after this installation , I can create extension for any public IP in the world and communicate freely.
thank you.

We don’t know about FreePBX. The people on should do.

In the case of Asterisk, the word extension has a different meaning, but, in the FreePBX sense, the answer is no, because, in some countries it will be against the law and some ISPs (particularly mobile phone based ones) will block VoIP traffic.