[This is pre-release documentation and subject to change in future releases. This topic's current status is: Milestone-Ready]

Topic Last Modified: 2010-03-31

This section describes the considerations you need to make about the regions, sites, and the links between sites in your topology and how those are important when you deploy Enterprise Voice.

In this release, the documentation addresses only a few of the topology considerations you need to make.

Sites and Regions

First, identify the sites in your topology where you will deploy Enterprise Voice and the regions to which those sites belong. In particular, consider how you will provide PSTN connectivity to various sites. For manageability and logistical reasons, the regions to which these sites belong can be a deciding factor. Decide where gateways will be deployed locally, where Survivable Branch Appliances (SBA) will be deployed, and where you can configure SIP Trunks (either locally or at the central site) to an Internet telephony service provider (ITSP).

Network Links Between Sites

You also need to consider the bandwidth usage that you expect on the network links between your central site and branch sites. If you have or plan to deploy resilient WAN links between sites, we recommend that you deploy a gateway at each branch site to provide local direct inward dial (DID) termination for users at those sites. If you have resilient WAN links, but the bandwidth on a WAN link is likely to be constrained, configure Call Admission Control for that link. Consider also enabling media bypass on constrained links if you have a gateway peer that supports media bypass.