AOR section is used for the the configuration for a location of an endpoint, is to tell Asterisk where an endpoint can be contacted, you just do that with trusted endpoints not with anoymous one If you dont want to allow anonymous calls remove the Endpoint 'anonymous
Sir you will need to define if you start using plain Asterisk or FreePBX because the issue here is that setting on FreePBX are done using the GUI and any solution we gave you here, it is assuming you will edit configuration files on this case /etc/asterisk/pjsip.conf file
easy way is remove the anonymous endpoint from your pjsip configuration also unloading the module res_pjsip_endpoint_identifier_anonymous.so will disable the anonymous authentication support