FreePBX as SIP router

I was wondering if anyone out there has successfully accomplished using FreePBX as a SIP router. I have several independent offices, all with their own FreePBX server and unique extension ranges. Now they have joined together under a universal management group and want to be able to dial extensions in other offices directly. I can set up IAX2 trunks and routes between the servers, but it will take awhile as there are over 30 offices. Using IAX2 trunks to sends the call to the FreePBX distro acting as a router, but it does not pass the call on to where it needs to go.