With Callback, a user does not have to repeatedly call a busy extension back, hoping to find it idle.
Programming for this Feature
Programming Call Waiting / Camp On
User Operation


When an extension user calls a busy co-worker, they can leave a Callback request for a return call. The system services Callback requests as follows:
  1. Caller at extension A leaves a Callback at extension B.
    • The caller can place or answer additional calls in the mean time.
  2. When extension B becomes idle, the system rings extension A. This is the Callback ring.
  3. Once the caller at extension A answers the Callback ring, the system rings (formerly busy) extension B.
    • If caller A doesn’t answer the Callback ring, the system cancels the Callback.
  4. As soon as caller B answers, the system sets up an Intercom call between A and B.

An extension user can leave a Callback at many extensions simultaneously. The system processes the Callbacks as the extensions become free. In addition, many extensions can leave a Callback at the same extension. The system processes these Callbacks on a first-in/first-out (FIFO) basis.

If an extension user leaves a Callback request and then fails to answer within four rings, the system cancels the Callback.

If an extension is set up to receive Camp-On tones for Intercom calls, and Camp-On tones are enabled system-wide, it will receive the tones when a user leaves a Callback.

Conditions and Defaults


  • A system reset or power failure cancels all Callbacks system-wide.

Default Setting

  • Callback enabled.

Release Notes (System)

CLEAR Key Menu Added

[3.00.35] While the telephone is idle, pressing CLEAR provides a menu for quickly clearing Callbacks or Call Forwarding at the extension. The CLEAR menu was not available in prior versions.

Reference: None

Other Related Features


  • Attendant Position
    • An extension user cannot leave a Callback for the attendant because the attendant’s extension is never busy.
  • Call Waiting / Camp-On
    • If an extension user starts to leave a Callback request but doesn’t hang up, the system Camps-On instead.
  • Central Office Calls, Answering
    • If a line is ringing an extension because of a prior Callback, and then receives a new outside call, it will start ringing for the new call. The Callback request is then queued.
  • Do Not Disturb
    • An extension cannot leave a Callback for a busy co-worker that is also in Do Not Disturb.
  • Line Queuing / Line Callback
    • An extension user can queue for a busy line and then hang up to turn the queue into a line Callback.

IntraMail Features

  • None.