Panasonic KX-TG7731S Service Manual page 19

Call Waiting Caller ID
Calling Identity Delivery on Call Waiting (CIDCW) is a CLASS service that allows a customer, while off-hook on an existing call,
to receive information about a calling party on a waited call. The transmission of the calling information takes place almost
immediately after the customer is alerted to the new call so he/she can use this information to decide whether to take the new
call.
Function:
The telephone exchange transmits or receives CAS and ACK signals through each voice RX/TX route. Then FSK data and
MARK data pass the following route.
Telephone Line→P101→L101, L102→C105, C106→R105, R106→R108, R107→IC501(23, 21).
If the unit deems that a telephone connected in parallel is in use, ACK is not returned even if CAS is received, and the
information for the second and subsequent callers is not displayed on the portable handset display.
Signal Flow
Telephone Exchange
Cordlessphone
Signal Flow
Cordlessphone Telephone Exchange
IC501
Call Waiting Format
CAS: CPE Alerting Signal
Dual Tone of 2130 Hz, 2750 Hz
-15 dBm (900 ohm load)
CAS
80 5 ms
0~100 ms 60 5 ms
CIDOUT
Pin 24
R108
CIDINn
Pin 23
R107
CIDINp
Pin 21
LSRn
Pin 28
KX-TG7731S/KX-TG7732S/KX-TG7733S/KX-TGA470S
Continuance Signal
of 1200 Hz (Data "1")
MARK
0~500 ms 58~75 ms
ACK: Acknowledged Signal
DTMF
"D"
ACK
C107 C103
R103 R101
R105 C105
C108 C104
R104 R102
R106
C106
19
"FSK"
DATA
about 300 ms
(be changed by
Information Volume)
L1T
L101
V
L102
L1R
P101