About Conditional Bandwidth CAC for Media Release

The Oracle® Enterprise Session Border Controller performs bandwidth CAC for SIP per realm, for each Address of Record (AoR) or IP address. The system checks bandwidth limits based on the codecs listed in SDP. If a new SIP INVITE contains codecs in an SDP message that exceed bandwidth available for a given resource, the system rejects that INVITE. This check occurs both on the ingress and egress sides of a call, and both sides must have enough available resources to support the call for it to be admitted.

In the case of calls where media is released, the Oracle® Enterprise Session Border Controller does not count bandwidth consumed by the call. However, this exemption is not given until the media is actually released—and media release conditions are unknown at the time SIP INVITE is admitted. This is because an INVITE received on one side of the Oracle® Enterprise Session Border Controller is only media-released when that INVITE is routed back through the Oracle® Enterprise Session Border Controller as a hairpin or other multi-system media release. So there has to be enough bandwidth for the initial INVITE; otherwise, and even if the INVITE is a candidate for media release, it will be rejected.

When there is a significant volume of such calls—ones that are candidates for media release, but cannot be admitted because of CAC limits—it becomes important to admit them so long as they truly end in media release. This feature thus allows admission of SIP calls that might otherwise be rejected because of bandwidth limitations when the far-end of the call causes media to be released.