Panasonic KX-FP701ME Service Manual page 35

6.5.5. Hook Switch (SW101)
When the handset is lifted, the switch turns ON, and the signal at pin 43 of IC1 becomes low.
When the handset is returned, the switch turns OFF, and the signal at pin 43 of IC1 becomes high.
ON-Hook
OFF-Hook
SW Signal (IC1-43 pin)
ON Low level
OFF High level
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KX-FP701ME