Checking Smart settings
Before switching to 'Smart' firewall settings, you can check which hosts and networks will be permitted through the firewall on any individual client machine by running the freepbx_m3_firewall.phar file with a -c or --check  option
[root@freepbx-server ~]# /usr/local/m3/freepbx_m3_firewall.phar --check
These hosts or networks will be permitted through the VoIP Firewall
        192.159.66.3
        66.243.108.101
        192.168.15.43
        203.99.99.0/255.255.255.0
        202.43.66.2
        202.43.66.3
        202.43.66.5
        202.43.66.1
        202.43.66.4
        10.0.0.0/255.0.0.0
        172.16.0.0/255.240.0.0
        192.168.0.0/255.255.0.0
[root@freepbx-server ~]# |
You can compare this list against what you're expecting to see, and if you are missing any entries you can fix them before committing the changes.