I found that a standard phone cord may not work to hard connect the base unit and the remote sensor / transmitter unit.
You may have to make a “cross over” cable by cutting and splicing the wires as follows:
- at one end, cut the four conductor phone cable about 12 inches from the end.
- connect the green wire to the red wire, the red wire to the green wire, the yellow wire to the black wire, and the black wire to the yellow wire.
Red -----------x--------Green
Green----------x--------Red
Black-----------x--------Yellow
Yellow---------x---------Black