Panasonic KX-T336 System Reference Manual page 204

14.00 Distinctive Busy Tone
Description
There are three busy tone patterns as follows:
Busy tone 1 : Normal busy tone.
Busy tone 2 : A unique busy tone which allows
users with busy tone detection
SLT's to use Busy Override, etc,
when encountering a busy line.
Busy tone 3 : A special busy tone sent when a
trunk is busy to inform the
extension user that Automatic
Callback to Trunk will be set by
going on-hook automatically.
Busy tones 1 and 2 are not used at the same
time. Only one tone is selected by "System-
Operation", Busy Tone.
If busy tone 2 is selected, PITS's follow the
setting.
Programming
System Programming
"System-Operation (1/3)",
Busy Tone
Reference
VT Dumb
9-D-1.01 10-C-4.00
3-B-23
Conditions
If Automatic Callback to Trunk is programmed,
the function is automatically set when making an
outgoing CO call and going on-hook when
hearing busy tone.
See Section 4-C-6.01, 5-A-4.01 "Automatic
Callback-Trunk" for details.
When the Automatic Callback to Trunk function is
enabled in system programming, special busy
tone is sent. When Automatic Callback to Trunk
is not enabled in system programming, busy tone
1 or busy tone 2 is sent. See Section 3-B-16.00
"Tone and Ringing Patterns" for the busy tone
patterns.