The ADTRAN Smart 16/16e shelf provides a rackmount, high-density solution for central site WAN connectivity requirements. The shelf provides flexibility, allowing installation of a mixture of 16 WAN communication devices. ADTRAN has a complete offering of ISDN, DDS, Switched 56, and FT1/T1 products that operate in the shelf. The Smart 16/16e shelf may be configured for 19" or 23" mounting with either AC or DC power. Load sharing and redundancy are provided with an optional second power supply. The shelf incorporates a mid-plane design that facilitates hot swapping for all devices, including the power supplies.This product is an upgrade shelf to provide existing 1st Generation Smart 16/16e customers the higher reliability of dual AC power inputs. This upgrade includes only the 2nd generation shelf and dual AC power interface card and requires the use of previously purchased AC power supplies and controller.