Panasonic KX-TC1872B Service Manual page 51

KX-TC1868B / KX-TC1871B / KX-TC1872B
lCall Waiting
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 CAS signal flows from T/R → R111, R112 collector → C111, C112 → IC501 pins 41~43 and the ACK (DTMF signal) is
returned to the telephone exchange. The telephone exchange that received the ACK can send the data in the same manner as the
caller ID. 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.
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