Inbound routing based on area code

I am currently using AsteriskNow v2.

What I am trying to accomplish is having all calls from an area code go directly to the person responsible for that area. While searching for a solution for this I did come across a post that had a few examples. So Josh at extension 1902 would receive all calls from the 808 area code.

exten => s,1,GotoIf($${CALLERIDNUM:0:3}" = "808?1902|1)

While asterisknow uses freepbx to control the config files. Where and how would I go about putting this into freepbx or another loaded config file that where something like the above would work. Thanks,