Panasonic KX-TD500 System Reference Manual page 610

5.00 Call Waiting
Description
Call waiting tone to a busy extension indicates
that another call (extension or CO) is waiting.
To set or cancel Call Waiting feature, dial the
feature number for "Call Waiting Set" or "Call
Waiting Cancel".
Programming
System Programming
"System-Numbering Plan (5/11)",
Call Waiting Set
Call Waiting Cancel
Conditions
The call waiting tone is not sent to a SLT which is
connected as a parallel connection.
Call waiting tone is sent in the following mode.
15 secs
Reference
VT Dumb
10-D-6.05 11-C-11.00
5-B-8
Operation
Setting Call Waiting
1. Lift the handset.
2. Dial the feature number for "Call
Waiting Set" (Default : Y52).
• You hear confirmation tone 1 or
2, and then dial tone 1, 3, or 4.
3. Replace the handset.
Canceling Call Waiting
1. Lift the handset.
2. Dial the feature number for "Call
Waiting Cancel" (Default : #52).
• You hear confirmation tone 1 or
2, and then dial tone 1, 3, or 4.
3. Replace the handset.