Sip-phones correctly registered but no sound

How can i get to Asterisk command prompt ?

Just the root prompt when physically on the FreePBX ?
Or
Do you refer to this : fwconsole pjsip set logger on ?
Because i use PJSIP and i can confirm you tomorrow (when at office) about Asterisk Settings (external address and local networks) you Ask.

Thanks a lot dear friend, if there is possibilities we can directly write on WhatsApp.