Figure 4-5. Rj11 And Rj14 Interfaces - AT&T MERLIN LEGEND Release 2.0 Installation Section

Connecting the Control Unit to the Network Interface
CAUTION:
Do not plug an analog multiline telephone, an MLX telephone, or
anything else from the telephone side of the control unit into this
wiring field; doing so will busy-out the trunk.
RJ11 and RJ14 Interfaces
The RJ11 and RJ14 interfaces are connected similarly, with the following
differences:
RJ11 connects one central office trunk per jack
RJ14 connects two trunks per jack
Plug a 267C-type adapter into each RJ14 jack.
See Figure 4-5:
Single-Line Adapter (RJ11)
2-Line Adapter (RJ14)
Figure 4-5. RJ11 and RJ14 Interfaces
(267C)
Wiring 4-11