Not hear nothing but only from 2 local extensions

i configured my asterisk server and freebpx 13 on Centos 7

I have only the problem when call from extension 1 to extension 2 because not hear nothing

If i call from my iphone to my voip number i have not problem

The same problem if i call from my voip number to my iphone, not hear nothing.

What can be? Maybe some port closed? or firewall block something?

I hope in some help
Thank you

Are the phones connected to local PBX (same subnet?)

I’ve had a similar issue before. Turns out the phones were echo cancelling each other as they were next to each other for system testing.

More Network info would help.