Grey Headline (continued)
Introduction
TANDBERG VIDEO COMMUNICATIONS SERVER ADMINISTRATOR GUIDE
Call Processing Diagram
One of the functions of the VCS is to route calls to their appropriate destination, based on the address or alias received from a locally registered endpoint or external zone.
There are a number of steps involved in determining the destination of a call, and some of these steps can involve transforming the alias or redirecting the call to other aliases. It is important to understand the process before setting up your dial plan so you can avoid circular references, where an alias is transformed from its original format to a different format, and then back to the original alias.
The VCS is able to detect circular references. If it does identify one it will
terminate that branch of the search and return a “policy loop detected” 
error message.
Search Process
The process followed by the VCS when attempting to locate a destination endpoint is shown in the diagram opposite.
1.The user enters into their endpoint the alias or address of the destination endpoint. This can be in a number of different formats.
2.The destination address is sent from the caller’s endpoint to its local VCS (i.e. the VCS to which it is registered).
3.The VCS applies any
4.The VCS applies any Administrator Policy to the (transformed) alias. If this results in a new alias, the process starts again, with the new alias checked against the
5.The VCS applies any User Policy (if FindMe is enabled) to the alias. If the alias is a FindMe name that resolves to one or more new aliases, the process will start again; all the resulting aliases will be checked against
6.The VCS then searches, in order of priority, all its zones, including the Local Zone (which includes any Peers). If the alias matches an ENUM zone, this may return a URI. If so, the process starts again; the URI is checked against any
7.If the alias is found within the Local Zone or by one of the external zones, the
VCS will attempt to place the call to that zone.
8.If the alias is not found, the VCS will respond with a message to say that the call has failed.
Introduction | Getting Started |
| Overview and |
| System |
| VCS |
| Zones and | Call | Bandwidth |
| Firewall |
| Applications |
| Maintenance |
| Appendices |
| Status |
| Configuration |
| Configuration |
| Neighbors | Processing | Control |
| Traversal |
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JULY 2008 |
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