Panasonic KX-TC1872B Service Manual page 50

KX-TC1868B / KX-TC1871B / KX-TC1872B
13.8. Calling Line Identification Circuit (Caller ID)
Function:
The caller ID is a chargeable 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 type 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.
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