8.
4.
FACILITIES
The system generates the following tones which are used in conjunction with the
available facilities.
Tones
Dial Tone
A continuous tone of
350
Hz and
440
Hz.
NU Tone
Engaged Tone
Direct Tone
Ringing Tone
Ringing Current
Facili
t
ie
s
A continuous tone of
440
Hz.
440
Hz tone
140
m sees ON
140
m sees OFF.
A
350
Hz continuous tone mixed with
440
Hz tone
interrupted
1
sec ON,
70
m sees OFF.
440
Hz tone interrupted
500
m sees ON,
1
sec OFF.
The system also generates its own ringing supply. This
is a
70
v peak to peak supply of
20
Hz applied at the
same cadence as the system ringing tone.
The following facilities are available to all extensions:
a.
Intercom calls
b.
Outgoing exchange line calls
c.
Receive incoming exchange line ringing
d.
Answer incoming exchange line calls
e.
Hold exchange line calls
f.
Transfer exchange line calls
g.
Conference calls on exchange line or intercom calls
h.
Divert intercom calls
Intercom Calls.
To make an intercom call, lift the handset and listen for system dial tone. If the
intercom circuit is busy no dial tone will be heard. On receipt of system dial tone, dial the
required extension number. If the called extension is free system ringing tone will be heard
and ringing at the same cadence connected to the required extension. If the called extension
is engaged on an exchange line call system engaged tone will be received. If the number
dialled represents a non-existant extension that has been closed at the CCU then system NU
will be received. If the spare extension has not been closed at the CCU no tone will be heard.
