Panasonic KX-TD612CE Installation Manual page 40

Installation
• Before making the connection of the Extension Connector to the PBX main unit, extension
lines should be checked carefully. If the extension lines are connected to the main unit with
those wires making a short circuit between the H-L pins or T-R pins, it may cause a
malfunction of the system, or may damage the circuit of the PBX system in the worst case.
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Installation Manual