Panasonic KX-TD612CE Installation Manual page 43

Method 2: Connection through the Modular Socket
4-conductor wiring cord
Connect pins "H" and "L" only.
("T" and "R" are not required.)
Installation Manual
Modular
Socket
Digital Proprietary Telephone
Modular
Socket
2-conductor wiring cord
Connect pins "T" and "R".
Single Line Telephone
Installation
43