Matsushita Electric KX-TSC35MXW, Service Manual

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9.4. Caller ID Detect Circuit
9.4.1. Function (FSK signal)
The caller ID is a changeable ID which the user of a telephone circuit obtains by entering a
contract with the telephone company to utilize a caller ID service. For this reason, the operation
of this circuit assumes that a caller ID service contract has been entered for the circuit being
used. The data for the caller ID from the telephone exchange is sent during the interval between
the first and second rings of the bell signal. The data from the telephone exchange is a modem
signal which is modulated in an FSK (Frequency Shift Keying) format. Data "0" is a 1200 Hz sine
wave, and data 1 a 2200 Hz sine wave.There are two types of the message format which can be
received: i.e. the single message format and plural message format. The plural message format
allows to transmit the name and data code information in addition to the time and telephone
number data.
9.4.2. Circuit operation
Caller ID / Caller ID signal is sent through the circuit via the following path: / TEL Line C551,
C552 R551, R552 Pin87,88 of IC801
10. BLOCK DIAGRAM
10.1. IC801
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