Separating groups of extensions

[comtech]

Restrict internal extension calls

Hi, I am currently using AsteriskNow which include this FreePBX. Now I am looking solution how to restrict calls. I have extension/extension groups 100 000 - 199 999 and 200 000 - 299 999. How I can make rule that only allow internal call between 100 000 - 199 999 extensions but not can’t make call 200 000 - 299 999? I have understand that I need to make modifications in sip_custom.conf and extensions_custom.conf? I have found those configuration files under /etc/asterisk/ but it’s only way…