HP ProCurve 7000dl Series Basic Management And Configuration Manual page 551

4. Enter the cable length setting so that the Secure Router OS can establish
the proper signal level. Enter:
Syntax: line-length <cable length>
Replace <cable length> with -7.5 or the length of the cable in feet, up to
655 feet.
5. Configure the signaling mode:
Syntax: signaling-mode [message-oriented | none | robbed-bit]
6. Activate the interface
ProCurve(config-t1 1/2)# no shutdown
Configuring the E1 + G.703 and T1 + DSX-1 Modules
Quick Start
9-27