TANDBERG D13691.03 user manual Call Policy, Making Decisions Based on Addresses, Address-switch

TANDBERG Border Controller User Manual

8Call Policy

Your TANDBERG Border Controller allows you to set up policy to control which calls are allowed and even redirect selected calls to different destinations. You specify this policy by uploading a script written in the Call Processing Language (CPL). Each time a call is made the

Border Controller executes the script to decide, based on the source and destination of the call, whether to

•Proxy the call to its original destination

•Redirect the call to a different destination

•Reject the call.

The Border Controller will only execute scripts for source or destinations which are registered directly with the system.

The CPL script is uploaded via the Web interface under the Border Controller Configuration → Files web page.

The execution of the CPL script is controlled by the setting

xConfiguration Gatekeeper Policy Mode <On/Off>

Policy interacts with authentication (section 5.2). If authentication is enabled on the local Border Controller and a call is received from a remote, unauthenticated Gatekeeper, the call’s source aliases will be removed from the call request before it is passed to the policy engine. This is because the unauthenticated source aliases could be forged and so should not be used for policy decisions in a secure environment.

The following sections give details of the Border Controller’s implementation of the CPL language and should be read on conjunction with the CPL standard (RFC 3880[5]).

8.1Making Decisions Based on Addresses

8.1.1 address-switch

The address-switch node allows the script to run different actions based on the source or destination aliases of the call. The address-switch specifies which fields to match and then a list of address nodes contains the possible matches and their associated actions.

The supported attributes on an address-switch and their interpretation are as follows:

field
origin	Match against the source aliases.
destination	Match against the destination aliases.
original-destination	Match against the destination aliases.

If the selected field contains multiple aliases then the Border Controller will attempt to match each address node with all of the aliases before proceeding to the next address node i.e. an address node matches if it matches any alias.

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