Operation - Bell System Practices TELEHELPER Identification, Installation, Connections, Operation, And Maintenance

When the speakerphone switch is operated to
•
the ON position the telephone set should be
disconnected from circuit and ringing or
called party should be heard through speak­
erphone
If beeping tone is heard check for weak bat­
•
tery, no battery, or loosened battery and cord
connections cover
Turn volume control knob, volume should
•
increase or decrease
Hold speakerphone rocker switch in QUIET
•
(nonlocking) position and check that speak­
erphone transmission is disabled, but receive
speech is still heard from loudspeaker.
5.

OPERATION

5.01
The following characteristics govern the use
of the speakerphone:
When dialing a number the speakerphone
•
rocker switch must be in the OFF position
When changing from telephone to speaker­
•
phone or back either the speakerphone or the
associated telephone set must be on the line
at all times to maintain connection with dis­
tant party
Note: When changing from telephone to
speakerphone turn the speakerphone on before
replacing handset on-hook. When changing
from speakerphone to telephone lift the handset
off-hook before turning the speakerphone off.
The speakerphone volume control knob ad­
•
justs only the receive volume and has no ef­
fect on the transmit level
When the speakerphone rocker switch is in
•
the ON position the associated telephone set
is disconnected from the line
When the speakerphone rocker switch is held
•
in the QUIET position transmission to the
BSP 512-750-100·i01-i01_198-Q9.jpg Scanned by Frank HarrelL (Cowboy Frank) Castle Rock, Colorado Feb 23,2012 22:59:37
distant party is prevented allowing a private
off-line conversation at the speakerphone
location.
Note: Operation of the rocker switch to the
QUIET position disables the voice-operated cir­
cuit (paragraph 5.03) and Jocks the speaker­
phone in the receiver mode with transmit
disabled.
Note: Incoming speech is not interrupted by
operation of rocker switch to QUIET position.
Extension telephone off-hook on same line
•
may result in degradation of receive speech
from loudspeaker on long loops due to reduc­
tion in line current to speakerphone.
5.02
The speakerphone provides an automatic indi-
cation of a weak battery. This is a low level
beeping tone from the loudspeaker which is only au­
dible when receiving speech. It is turned off when
transmitting so that it is not transmitted to the other
party. Test for a weak battery can be performed by
depressing the rocker switch to its QUIET position
and holding it operated while listening for the
beeping tone.
5.03 The speakerphone is provided with a voice
operated circuit which enables only one direc­
tion of transmission (either transmit or receive) at a
time. This is required to avoid "singing" which would
otherwise occur due to acoustic feedback from the
loudspeaker to the microphone. When neither party
is talking or when transmit speech is present at a
higher level than receive speech, the voice operated
circuit enables speakerphone transmit and disables
receive. In order to switch the speakerphone into the
receive mode (enable receive, disable transmit) the
receive speech must be higher than the switching
threshold and in addition must be higher than the
transmit speech (if present) and any noise at the
speakerphone location. Speakerphone installation in
a noisy location should be avoided since it will result
in poor performance where portions of words are
clipped or even complete words and sentences are
missed.
ISS 1, SECTION 5 1 2-750- 1 00
Page 9