Callback, Busy Extension/Call Completion

Definition

The ability to initiate a supervision on a busy extension, and be automatically rung when the dialed extension becomes free.

Settings

For normal use, there is no CoS for Callback, but the special CoS for ‘automatic callback request at calls from an external device’ is set by the administrator.

Procedure and function

The calling party dials a suffix digit when the busy tone is received. A confirmation tone is sent to acknowledge the supervision. Both parties are supervised and, whenever concurrently free, a connection is established. The calling party is rung with a special Callback ringing signal. If the calling party cannot be alerted, or does not answer within a predefined time, the supervision is either (if possible) re-initiated (as a reverse Callback) or canceled. Manual cancellation of a Callback order is done via a procedure from the phone.