Panasonic KX-TG2559LBS, Service Manual

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12.5. 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. This model can receive 2 types of Caller ID (FSK type, DTMF type)
•
FSK type
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 or 1300 Hz sine wave, and data 1 a 2200 Hz or 2100 Hz sine wave.
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KX-TG2559LBS