This read-write object sets the T1 line build-out distance in five 133-foot bands from 0 to 655 feet, valid only for the T1 interface. Line build-out compensates the T1 transmitter's output signal shape for the specific cable length to the connected T1 equipment, so setting it to a value shorter than the actual cable run can result in a signal that arrives too attenuated or distorted for the far end to reliably decode, while an unnecessarily long setting can over-drive a short cable run. For a T1 mux located roughly 300 feet of cable away from the modem, an admin would select the 266-399 foot band to properly shape the T1 output for that specific distance rather than leaving it at the default short-distance setting.