As an analog voice terminal user, you can activate supplementary service - Call Completion to Busy Subscriber (SS-CCBS) by pressing the Recall button or flashing the switch hook, then dialing the Automatic Callback Activation Feature Access Code. You can activate only one Automatic Callback call at any given time.

As a multi-appearance voice terminal user, you can activate SS-CCBS for the number of Automatic Callback buttons assigned to the terminal. After placing a call to a voice terminal over the DSS1 network that is busy, you can activate SS-CCBS by pressing an idle Automatic Callback button.

In the above two scenarios, the called station is located in the public network. The public network access must be located in the same switch as the station.

When you request a CCBS supplementary service it remains active until the Call Completion is performed or until the Service Duration timer expires. The default for the timer is set to 40 minutes. The terminal must be located in the same switch as the public network access.

When SS-CCBS is activated towards the busy station on the terminate side (public network or PBX), the terminating side monitors the called voice terminal. When the called voice terminal becomes available to receive a call, the terminating side notifies the originating side of the possibility of executing a Call Completion call attempt. The originating side then originates the Call Completion call.

A busy voice terminal becomes available when the user hangs up after completing the current call.

A SS-CCBS request is canceled for any of the following user-related reasons: