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CM-TB8T Telephone Hybrid Expansion Card 12
preset by the dim potentiometer. The channels 4W input is not used in this
mode.
To use a connected telephone channel in IFB mode:
put the IFB/4W switch
in the IFB 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. The signal form the selected
IFB input, either the channels own 4W IN input or one of the dedicated
programme inputs, IFB A or IFB, is routed to the telephone line. When the
talk button is pressed, the signal routed to the connected telephone line is
either replaced by or mixed with the microphone signal, and the level of the
feed to the loudspeaker (not headphones/headset) is reduced by the level
preset by the dim potentiometer.
Once a telephone enabled talk channel is active, the corresponding talk
button illuminates red and the handset is automatically disconnected from
the telephone line.
Ending a Telephone Call
To end a telephone call, briefly press the channels talk button whilst holding
the rotary control. If an external handset is still off hook, the line will not
disconnect from it. The handset must be replaced to fully clear the line.
The telephone enabled channel can also be configured to automatically
disconnect a telephone call when the predefined line conditions or
disconnect tone are detected. These conditions are defined as part of the
selected country code settings and do not need to be configured separately.
An option to enable auto disconnect is in the PSTN settings page of the
embedded web server.
Embedded Web Server
When the PSTN telephone expansion card is fitted, an additional web page
is available for configuring related settings. The PSTN Settings page appears
under the Configuration tab.
PSTN Settings Page
Fig 12-2: PSTN Settings Page
Telephone Numbers 1-8:
The CM-TB8 can stored up to 8 telephone
numbers that can be accessed by both of the telephone interface channels.
Enable Call Signal:
When an external caller is ringing one of the telephone
interface channels, this option routes an internally generated call signal to
the monitor headphones/headset and loudspeaker. The signal matches the
cadence pattern of the ring signal.
