KX-TS2388RUB, KX-TS2388RUW, KX-TS2388CAB, KX-TS2388CAW, KX-TS2388UAB, KX-TS2388UAW - Panasonic Telephone Service Manual (repair manual). Page 11

11

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 sec-
ond 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 for-
mat which can be received: i.e. the single message format and plural message format. The plural message format allows to trans-
mit the name and data code information in addition to the time and telephone number data.

• FSK (Frequency Shift Keying) format

Caller ID signal is sent through the circuit via the following path :
LINE 

 C500/C520  C551/C552  R551/R552  R553/R554  IC801 (pin 92, 93)

STD Ring / 20Hz
Tip-Ring

FSK

DATA in

1st Ring

Silent interval

2nd Ring

DATA

0.1Vrms

70Vrms

1300Hz or
1200Hz
=DATA "0"

2100Hz or
2200Hz
=DATA "1"