Features LTPH-UM-1234-012 April 30, 2003 HDU-409 Lists 1, 2, and 3F EATURES• The unit occupies one standard 239 T1 mechanics slot.• Powered by any doubler-compatible HiGain or PG-Flex (List 2 or List 3only) Central Office (CO) line unit.• Front-panel status display Light Emitting Diode (LED).• Lightning and power-cross protection on both sides of the High-bit-rateDigital Subscriber Line (HDSL) interface.• Extremely low power dissipation.• Extremely low latency.• Can be used in four-span line-powered circuits (three doublers and oneremote) or five-span locally-powered circuits (four doublers and oneremote).• Compatible with PG-Flex List 3x line units in configurations with up tothree spans.• Complies with the applicable requirements of Network EquipmentBuilding System (NEBS) Generic Equipment requirements of GR 1089CORE and GR 63 CORE compliance.• Minimal wander and jitter.