12 CM-TB8T Telephone Hybrid Expansion Card
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Making a Telephone Call
A telephone call can be made using an external telephone handset, or
directly by dialling one of the stored numbers.
Direct Dialling
The CM-TB8 can store 8 telephone numbers for direct dialling. These are
entered using the embedded web server. To dial a stored number, press
and hold the rotary control and then briefly press the talk button of the
required channel, either 1 or 2. The rotary control can then be released.
The talk buttons on channels 1 to 8 will illuminate amber if a valid
telephone number has been entered in the corresponding telephone
number edit on the PSTN page of the web server. For example, if telephone
numbers have previously been entered in positions 4 and 7, then only the
talk buttons on channels 4 and 7 will illuminate.
To dial the number, press one of the illuminated talk buttons. If no
button is pressed within 3 seconds, the unit reverts to its previous
state and the direct dialling mode is cancelled. When a valid number is
selected, the unit will connect to the telephone line and dial the number
and the corresponding talk button will illuminate amber. The audio on
the telephone line can be monitored on the headphone/headset and
loudspeaker outputs at the level set by the channels own monitor level
potentiometer.
Dialling Using an External Telephone Handset
Simply lift the receiver and dial the required number. The talk button on the
corresponding channel will fast flash amber to indicate the handset is off
hook. The talk button can be pressed to open the telephone line connection
to the CM-TB8 in parallel with the handset if required. The talk button
will then illuminate amber and the audio on the telephone line can be
monitored on the headphone/headset and loudspeaker outputs at the level
set by the channels own monitor level potentiometer.
Receiving a Telephone Call
An incoming telephone call will cause the talk button on the corresponding
channel to flash in the cadence pattern of the ring signal. If an external
telephone handset is connected, this will ring in the normal way. The call
can be answered by either pressing the talk button or lifting the handset. If
the handset is used to answer the call, the talk button will fast flash amber
to indicate the handset is off hook. If the handset is replaced prior to the
talk button being pressed, the call is dropped. If the talk button is pressed,
the CM-TB8 is connected to the telephone line and the talk button will
illuminate amber.
The telephone enabled channel can also be configured to automatically
answer an incoming telephone call. This is done in the PSTN settings page
of the embedded web server. If enabled, the call will be answered after 2
rings. For double cadence ring tones, both rings in the cadence pattern will
be counted.
Handling a Connected Telephone Call
Once a telephone call is connected to the unit, the talk button on the
corresponding channel illuminates amber. The channels audio call
indication illuminates the talk button green when the signal from the
telephone line rises above -12dB. The routing of audio through a telephone
enabled channel depends on the selection of the IFB/4W switch.
To use a connected telephone channel in 4W mode:
put the IFB/4W switch
in the 4W position. In this mode, the signal from the connected telephone
call is routed to the headphones/headset and loudspeaker at the level set
by the channels own monitor level potentiometer, with the overall level
controlled by the MON level potentiometer. The signal is also routed to the
talkback output at the TB OUT connector. When the talk button is pressed,
the microphone signal is routed to the telephone line, and the level of the
feed to the loudspeaker (not headphones/headset) is reduced by the level
