Call Admission Control
Call admission control (CAC) is, at a high level, a mechanism that is designed to protect a network from becoming overloaded by voice and video traffic. Simply put, CAC prevents users from establishing calls that result in a degradation of quality for the existing calls.
CAC should not be confused with Quality of Service (QoS), although the net results can be similar. QoS focuses on prioritizing certain types of traffic or traffic between a specific source and destination to guarantee certain levels of quality. Although this might be layered into a Communications Server design to ensure that a particular number of calls or video streams can be maintained, CAC is capable of tracking calls and not just tracking packets. ...