Its (Integrated Telephone System) And Monitor Section; Tam Interface Section (Kx-Ft981 Only) - Panasonic KX-FT981LA-B Service Manual

6.8.

ITS (Integrated Telephone System) and Monitor Section

6.8.1. General
The general ITS operation is performed by the modem IC5. The alarm tone, the key tone, the calling tone and the beep are output
from the ASIC IC1 (digital board).
6.8.2. Telephone Monitor (KX-FT981 only)
1. Function
This is the function when you are not holding the handset and can hear the caller's voice from the line.
2. Signal path
Refer to Check Sheet for Signal Route (P.114)
6.8.3. Speakerphone Circuit (KX-FT987 only)
1. Function
The circuit controls the automatic switching of the transmitted and received signals, to and from the telephone line, when the
unit is used in the hands-free mode.
2. Circuit Operation
The speakerphone can only provide duplex.
3. Signal path
Refer to Check Sheet for Signal Route (P.114)
6.8.4. Handset Circuit
1. Function
This circuit controls the conversation over the handset, i.e. the transmitted and received voices to and from the handset.
2. Signal path
Refer to Check Sheet for Signal Route (P.114)
6.8.5. Monitor Circuit for Each Signals
1. Function
This circuit monitors various tones, such as 1 DTMF tone, 2 Alarm/Beep/Key tone/Bell 3 Dummy ring back tone.
2. Signal path
Refer to Check Sheet for Signal Route (P.114)
6.9.

TAM Interface Section (KX-FT981 only)

1. Function
When TAM is connected to this unit, the unit receives documents for FAX calls or the external TAM records a voice message
automatically.
2. Circuit Operation
The TAM INTERFACE circuit consists of a CNG signal from the other party's detection circuit, VOX detection circuit (to judge
sound/no-sound) and RLY101 (to separate EXT. TAM).
a. CNG/VOX signal detection circuit
The CNG signal from the other party's FAX is detected in MODEM IC5 (digital board).
b. Remote receiving
This is the parallel connected DTMF signal for the TEL mode between a and b. When the other party is a FAX, the unit
changes to FAX receiving.
3. Signal path
Refer to Check Sheet for Signal Route (P.114)
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KX-FT981LA-B / KX-FT987LA-B