• A congestion alarm is raised.

• Calls that exceed the CAC maximum values are not allowed.

• Calls from extensions to public trunks through Alternate Route Selection (ARS) are queued and display Waiting for Line.

• Calls from extensions to public trunks which do not route through ARS receive a fast-busy tone and display Congestion.

• Idle phones display Emergency/Local calls only.

• Alternative routing to a local PSTN gateway follows ARS priority escalation rules.

• SIP calls that would exceed call limits and have no other targets are declined with cause=486 or cause = 503.

Allowed calls

When CAC limits have been reached, the following calls are allowed.

• Emergency calls are always allowed.

• Established calls are never torn down to achieve limits.

• A phone on a remote site that parks a call is always allowed to retrieve it.

• Request Coaching Intrusion calls are allowed.