The Automatic Callback (ACB) service allows users to monitor a busy party and automatically establish a call when the busy party becomes idle. Upon reaching a valid ACB busy condition, the users hear an announcement asking if they would like to monitor the line and be called back when it is idle. To activate ACB, the subscriber enters the digit prompted for and then goes on-hook. As soon as the called party becomes idle again, ACB attempts to re-establish the call between the subscriber and the previous busy party. The ACB service can only be activated against a destination within the same group. ACB can be enabled and disabled by the user.
Automatic Callback is an outgoing call feature that allows a user to place a call to another phone in the same group. If the phone you called is busy, the call originator can activate Automatic Callback to be notified when the called telephone is idle. When notified, a new call will be made to the idle telephone automatically and the originating user is not required to redial the phone number. The new call attempt is treated as an originating call attempt; it could receive busy treatment or be redirected (such as if call forwarding was now enabled.) For the new call setup to be attempted, both parties must be available.
The phone you are trying to connect to is considered busy or unavailable, if they cannot receive a call at their primary locations. This means that if a terminating feature redirects the call and the new location is busy, ACB is not activated. ACB is also disabled, if the call is handled by any of the following terminating services, that is, Selective Call Rejection and Selective Call Acceptance, but is not limited to these service interactions.
After activating ACB, the subscriber goes on hook and is notified with special ringing when both parties are idle. If the user answers special ringing, call setup is automatically initiated towards the other party. ACB has several operating parameters that are configured at the system:
Monitor Minutes: The amount of time to camp-out on the busy line, waiting for it to become idle. (30 minutes)
Retry Originator Minutes: The amount of time to wait before re-trying a busy Automatic Callback originator (the owner of the ACB session). ( 5 minutes)
Max Sessions: The total number of outstanding ACB sessions for one subscriber. ( 5)
Max Retry Rings: The maximum number of rings when alerting the originator that the terminator is available. (6) Max Time To Retry: Total amount of time to alert an originator that has been busy (unavailable). How long ACB tries to alert a busy originator. (180)
Activation of Automatic Callback is when a subscriber originates a call to another subscriber in the group, if the called party is unable to receive the call because of a valid ACB busy condition, a prompt is played giving the originator the opportunity to activate ACB (for example, "The line you are calling is busy. Press 1 if you would like to be notified when the line is available"). And to Deactivate Automatic Callback, a user that has activated ACB can also deactivate all outstanding ACB requests. On the phone simply dial #8 to cancel all outstanding requests by that user.