Session Manager CAC limits bandwidth between locations. For CAC, the links between locations can have limited capacity, while calls that take place entirely within a location do not need to be limited. CAC also assumes that all calls entering or leaving a location use the same network link. A link for the location connects the location to the public network, from which every other location can be accessed at equal cost. Any media session between locations involves two links – one link to each location, and another link from each location.

The association of one link to one location means that limits on links can be implemented as limits on locations. No other links are recognized or have limits enforced by CAC. Calls contained entirely within a location involve no links.

CAC enforces limits by allowing calls on a first-come, first-serve basis until a limit is about to be violated. CAC prevents limit violation by either reducing the bandwidth of calls or by denying calls. Bandwidth reduction can mean that audio or video quality is reduced, or that media streams (such as video) are removed. Only calls that would otherwise violate limits will be impacted by CAC. By preventing limits from being exceeded, CAC prevents packet loss degradation from impacting existing calls.

Calls between locations are subject to the limit enforcement of both locations, if limits have been defined for both. In cases when call parties are not mapped to locations, then CAC restrictions do not apply for those parties.

Emergency calls are never impacted by CAC.