I understand from the documens that, in order to enable users outside the firewall to communicate with internal users, an Edge Server must be deployed.
But, in a scenario where the company HQ with internal OCS deployment is connected via WAN with a remote branch office, it is mandatory to deploy a second OCS server only for the local branch users ? Is the RTP traffic routed locally between peers in the local network, or it is routed passing through the remote HQ OCS server as the signaling traffic ?
You don't not have to deploy OCS at the branches. I'm testing OCS 2007 with two branches, one in Sweden and one in the UK. They both use our local OCS infrastructure in Iceland. But both branches are connected to HQ with IPSec VPN connections.
To allow remote user access you have to deploy an Edge Server.