Operational Features

few seconds. This condition is not abnormal during

Operational Features

periods of heavy traffic.

Any standard 600-ohm telephone can be used in

Within the ship, disconnect can only occur when

the system. The type G telephone is normally used, but

both the calling and the called parties hang up.

the other types are suitable.

Ship-to-shore disconnect occurs when the ship's

All telephone numbers used in the system have

station hangs up, regardless of what the shore station

three digits. They consist of a hundreds, a tens, and a

does.

units digit. They are preassigned during installation,

EMERGENCY.-- Any telephone dialing 211

but may be changed by a wiring change. Each station

will automatically be connected to the predetermined

should be supplied with a copy of the ship's telephone

emergency station for that time period. This cut-in

directory. The directory is unique to a particular ship.

happens even if the emergency station is busy. The

A person using the telephone system will hear four

emergency stations are 201 quarterdeck, 203 alternate

distinct tones from the receiver during normal

quarterdeck, or 222 pilothouse. The station to receive

operation. These tones give information to the status

emergency calls is determined by a three-position

of a call. These tones are as follows:

switch at the central office switchboard.

Dial Tone. 600 Hz interrupted 120 ips. The

RESTRICTED LINE.-- Telephone stations

telephone is off-hook and the central office

connected as restricted are prevented from accessing

switchboard is ready to receive dial pulses.

the manual switchboard; therefore, they are unable to

connect to shore lines. This feature is established for

Busy Tone. 600 Hz interrupted 60 ips. The

a station at the central office switchboard. If a

called station is off-hook or all trunks/links are

restricted station tries to call the manual switchboard,

busy.

a busy tone will be returned. Additionally, if the

Ring-back Tone. 333 Hz modulated with 20 Hz

manual switchboard attendant calls a restricted line, a

interrupted at the same rate as the ringing

busy tone will be returned.

period (1 1/4 seconds on, 2 3/4 seconds off).

EXECUTIVE CUT-IN.-- Executive cut-in

The ringing voltage is being sent to the called

allows a station to complete a call even if the called

station.

station is busy. This feature is also known as executive

right-of-way. The cut-in connection does not

Howler Tone. 600 Hz interrupted at 8 ips. The

disconnect the original call, just joins it. To obtain

howler tone is a loud, raucous sound intended

cut-in, the user dials the digit 1 after getting a busy

to alert personnel across the compartment or in

tone. This feature is established for a station at the

the next compartment of the situation. There-

central office switchboard.

fore, it is uncomfortable if the receiver is held

close to the ear. You should avoid the condi-

HUNT-THE-NOT-BUSY.-- A telephone dialing

tions that make the howler sound. These condi-

a number in a hunt-the-not-busy group will be

tions are as follows:

connected to the next higher idle number in the group

if the called number is busy. The numbers in the group

-- Telephone receiving dial tone and dialing is

must have consecutive units digits with common

not started in 30 seconds.

hundreds and tens digits. For purposes of this feature,

-- More than 30 seconds elapses between dialed

the O is the highest number in the units digit group. If

digits.

the search reaches the O, and it is busy, a busy tone is

returned to the caller. This feature is established for a

-- Busy tone is received for more than 30

chosen group of numbers at the central office

seconds.

switchboard.

Hanging up the offending telephone will silence

the howler and return the telephone to normal status.

Test Equipment

If the telephone is not hung up within 2 minutes, an

alarm sounds in the central office switchboard.

The tools and test equipment required to trouble

shoot and repair the central office telephone system

Sometimes due to the number of calls in process

are listed in table 6-14.

at the same time, the dial tone may be delayed for a

6-68