Iwatsu ENTERPROSE-CS Owner's Manual page 224

Busy Intercom Callback
Analog SLT only. Not supported on SIP phones.
When you make an intercom call and the extension is busy:
 Do not hang up.
 Press and release the receiver button quickly.
 Wait for the dial tone.
 Dial the Busy Intercom Callback code
 Wait for a confirmation tone.
 Hang up.
To cancel:
 Lift the receiver.
 Wait for the dial tone.
 Dial the Cancel code
 Dial the Busy Intercom Callback code
 Wait for a confirmation tone.
 Hang up.
Busy Number Callback
Analog SLT only. Not supported on SIP phones.
When you dial an outside number and there is no answer or a busy signal:
 Do not hang up.
 Press and release the receiver button quickly.
 Wait for the dial tone.
 Dial the Busy Number Callback code
 Wait for a confirmation tone.
 Hang up and the ECS will call you back periodically to try calling again.
To change the callback interval:
 Dial the desired interval time in minutes
When your phone rings:
 Lift the receiver.
The number will automatically be dialed.
To cancel:
SIP & SINGLE LINE TELEPHONE USER GUIDE - 206

.
.
.

.
before you hang up.