3-20 DBS 576HD (USA) issued September 2001 576-50-700Chapter 7. SLT Features Section 700 - OperationCO Trunk Interface - DIDThe DID feature allows an extension to have a dedicated direct number. The dedicated number allowscalls to be made directly to the extension, without the caller going through the attendant.The DID number may have from 1 to 4 digits (typically 4).Each DID Trunk Interface card (VB-44520) supports up to 8 DID trunks.Hardware Requirements• The -48V power supply is required.Related Programming• N/AConsiderations• The DID Trunk card supports 1 to 4-digit dial-pulse (10 pps) or Dual Tone Multifrequency(DTMF) signaling.• DID numbers must be between 0 and 9999.CO Trunk Interface - Ground StartGround start trunks are supported in the System with the VB-44511 Loop Start/Ground Start trunkinterface. Each card supplies 8 circuits that can be individually configured for either loop start orground start operation.Ground start trunks are useful in preventing call collision.Hardware Requirements• When ground start trunks are used, the -48V power supply is required.Related Programming• N/AConsiderations• N/ACO Trunk Interface - ISDN BRIThe System supports ISDN BRI with the VB-44530 ISDN BRI interface unit. The VB-44530 is a T-Point ISDN-BRI that supports 2 B (bearer) channels and 1 D (data) channel (2B + D; 192kbps). Thisunit connects to an ISDN Data Service Unit (DSU). Point-to-point and point-to-multi operations areselectable.The ISDN-BRI supports enblock setting and enblock setting at the sub-address.Hardware Requirements• N/ARelated Programming• N/A
