Panasonic KX-NS1000 Operating Manual page 39

To answer the callback ringing from an idle extension
PT/SLT/PS
While hearing a callback ringing
R.B.Tone
Off-hook.
To answer the callback ringing from an idle outside line
PT/SLT/PS
While hearing a callback ringing
Off-hook.
•
If you do not answer the callback ringing within 10 seconds, this feature will be cancelled.
To cancel callback ringing (Automatic Callback Busy Cancel)
PT/SLT/PS
Off-hook.
Setting Callback on an ISDN Line (Completion of Calls to Busy Subscriber
[CCBS])
You can set the telephone to receive callback ringing when a busy called party on an ISDN line becomes
free.
When you answer the callback ringing, the called party's telephone number is automatically dialled.
Talk.
outside
phone no.
Dial outside phone
number.
4 6
C.Tone
Enter 46.
1.2.4 When the Dialled Line is Busy or There is No Answer
Talk.
On-hook.
Operating Manual 39