i am in the process of Pre-sales, where a small customer has an HQ with CME and he has 8 intl branches.
All the branches are connected through VPN for Data transfer, solution provided is to install an IP phone in each location and register the IP Phone with the CME in the HQ. it works perfect, my concern is the QOS, i am wondering if there is a way to limit the number of calls within the CME or consider the remote branches as regions like in the CCM.
No, CME doesn't have concept of regions at all.
All you can do is configure g729 for the remote phones to reduce bandwidth. If you get the newer phones (79x5), in the future you will be able to support iLBC that is much better than g729 for that purpose.
Hope this helps, please rate post if it does!