Iwatsu ENTERPROSE-CS Owner's Manual page 225

 Lift the receiver.
 Wait for the dial tone.
 Dial the Cancel code
 Wait for a confirmation tone.
 Hang up.
Busy Outside Line Queuing
Analog SLT only. Not supported on SIP phones.
When attempting to make an outside call and all lines are busy:
 Do not hang up.
 Dial the Busy Outside Line Queue code
 Wait for a confirmation tone.
 Hang up.
The ECS will call you back when an outside line becomes free. If you
previously dialed the outside number, that number will automatically be dialed
when the receiver is picked up.
To cancel:
 Lift the receiver.
 Wait for the dial tone.
 Dial the Cancel code
 Dial the Busy Outside Line code
 Wait for a confirmation tone.
 Hang up.
Call Park / Swap
When you have a call on Call Park and are involved in a second call and wish
to alternate between calls:
 Press and release the receiver button quickly or press the Flash key. (or
for Polycom press Hold).
 Dial the Call Park code
that was on Call Park and the second call will be placed on Call Park.
You may continue to alternate between calls by repeating the above procedure.
SIP & SINGLE LINE TELEPHONE USER GUIDE - 207
.

.
.

and you will be connected to the call
.