Verilink AS4000 (34-00244) Product Manual - Manual (Page 170)

Quad DS-1 with xDSL
11-4 Verilink AS4000 User Manual
The first pair of wires is connected to T1 and R1. When used, the
second pair is connected to T2 and R2, and in rare situations
requiring a line-powered doubler, power to the in-circuit doubler
can be derived from the pair LPWR+ and LPWR-.
NOTE: Terms like "receive pair" and "transmit pair" are not used in
xDSL. Each pair carries both transmit and receive signals.
Figure 11-3 Quad HDSL Interface - Rear View