Retargeting LRT ENUM-based Requests

Request re-targeting is when a target or a request as indicated in the Request-URI, is replaced with a new URI.

The happens most commonly when the "home" proxy of the target user replaces the Request-URI with the registered contact of that user. For example, the original request is targeted at the Address-of-Record of bob (e.g. sip: [e-mail]). The "home" proxy for the domain of the original target, example.net, accesses the location service/registration database to determine the registered contact(s) for the user (e.g. sip:bob@192.168.0.10). This contact was retrieved in a REGISTER request from the user's UA. The incoming request is then re-targeted to the registered contact. When retarget-requests is enabled, or the original Request-URI is the Oracle® Enterprise Session Border Controller itself, the URI from the LRT lookup is used as the new Request-URI for the outgoing request.

When a request is routed rather than re-targeted, the Request-URI is not changed, but one or more Route headers may be inserted into the outgoing request. Sometimes a request which already contains Route headers will be routed without adding additional Route headers.

When the Oracle® Enterprise Session Border Controller routes requests and the original Request-URI was not the Oracle® Enterprise Session Border Controller itself, the URI from the LRT /ENUM lookup is added as the top Route: header including the "lr" parameter. The Request-URI then remains unchanged.

Whether the Oracle® Enterprise Session Border Controller re-targets or routes a request depends on the following:

• The target (Request-URI) of the received request
• The presence of Route headers
• Local Policy Attributes,
• Registration Cache matching.

If the original target is the Oracle® Enterprise Session Border Controller itself (i.e. the Request-URI contains the IP Address in the SIP interface the request was received on), the request is always retargeted. When the original target is not the Oracle® Enterprise Session Border Controller and Local Policy is applied, the request will be re-targeted when the policy attribute action parameter is replace-uri. The request will also be re-targeted when the policy attribute specifies an ENUM or LRT lookup.

Retargetting requests can be configured in either the ENUM or LRT config depending on the request URI retrieval method choosen.