Information Tones
The signal which are transferred
between the telephone set and the exchange represent various
meanings which are referred to as different
types of information tones . The various types of
tones are as follows .....
-
Dialing tone which has been mentioned earlier is to inform the subscriber
that the exchange is now prepared to receive the B-number to be dialed
.
-
Ringing tone is to inform the A-subscriber that the exchange has established
the connection to the B-subscriber and the B-subscriber
is ringing .
-
Engaged tone is to inform that the B-subscriber is busy and connection
cannot be established. This tone complements the ringing tone .
-
Special information tone has two meanings. One is to inform the subscriber
that a fault has occurred and connection cannot be established. The other
is that a subscriber has requested the telephone administration to intercept
a call connection which has been established. This is only applicable if
the interception subscriber has the service facility. The special information
tone, where this applies, also replaces the ringing tone in the signal
diagram.
-
Congestion tone is to inform the subscriber that the equipment to be used
in establishing the call are fully utilized or blocked because they are
faulty. This tone also complements the ringing tone .
-
Intrusion tone is used when third party interrupts the call. The third
party could be the operator.
Apart from signaling between the telephone and
the exchange , there are also signaling
between one exchange and another exchange.
Figure shows the cadence for the various tones.
INDEX