Specifications

Introduction
1-13
The ISDN IDBU supports AT&T 5ESS, NTI DMS-100, and National ISDN-1 switch
types. Appendix B provides a checklist to use when ordering Basic ISDN Service from
your local telephone company.
Model for EDRS
The Excalibur Multirate DAP is also available in a model designed to operate with the
Excalibur Dial Restoral System (EDRS). This model is called an Excalibur Multirate
Dedicated Access Device (DAD). The EDRS provides dial backup by routing data
transmission to dial backup lines whenever a dedicated digital circuit fails. The EDRS
provides dial backup for Excalibur Multirate and Excalibur Multiport DADs in both
point-to-point and multidrop applications.
The EDRS allows concurrent dial backup of up to four dedicated circuits (point-to-point
and/or multidrop) per card carrier. For example, four 3-drop multidrop circuits can be in
dial backup at the same time. In a 6-card carrier system (one full rack), the EDRS allows
concurrent dial backup of up to 24 circuits.