Panasonic KX-FLB852CX Service Manual page 251

KX-FLB852CX / KX-FLB852CXS
7.12.23. OPTION HANDSET HOOK SWITCH
When the option handset is raised, the switch is turned off, and the signal of IC600-K16pin becomes low level.
When the option handset is settled, the switch is turned on, and the signal of IC600-K16pin becomes high level.
Signal (IC600-K16pin)
ON HOOK High level
OFF HOOK Low level
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