Specifications

Excalibur Multirate DAP Installation and Operation
1-12
DIGITAL LINE
FAILURE
EXCALIBUR DAP EXCALIBUR DAP
DIAL BACKUP LINE
CPU
DTE
Figure 1-4. Dial Backup Connection
Switched 56 IDBU operates at 56 Kbps over MCI's Switched 56 Service, AT&T's
Accunet Switched 56 Service, or Sprint's Enhanced Switched 56 Service, which does not
require suppression of echo cancelers. It complies with all requirements of AT&T's
Accunet Switched 56 Service, with AT&T Publications 62310 and 41458, and with
Sprint's Specification TS-0046. The IDBU accommodates a nominal loop loss of 0 to -31
dB which complies with the requirements of AT&T Publication 62310. It automatically
operates in extended range to accommodate loop loss from -32 to -45 dB. The
performance in this range is dependent on the telephone company equipment.
The ISDN IDBU operates over the ISDN Basic Rate service. This service provides two
full-duplex 64-Kbps channels (B-channels) for transporting data and one full-duplex 16-
Kbps access channel (D-channel) for carrying control or signaling information. The
ISDN IDBU operates on one 64-Kbps B-channel and the 16-Kbps D-channel. The IDBU
complies with the following documents:
• All requirements of ANSI North American Standard T1.601 - 1992, "Integrated
Services Digital Network (ISDN) - Basic Access Interface for Use on Metallic
Loops for Application on the Network Side of the NT (Layer 1 Specification)."
• All network requirements of Bellcore Special Report
SR-NWT-001937, Issue 1, Feb. 1991, "National ISDN-1."
• Bellcore Technical Reference TR-TSY-000793, Issue 1, Oct. 1988, "ISDN D-
Channel Exchange Access Signaling and Switching Requirements (Layer 2)."
• Bellcore Technical Reference TR-TSY-000268, Issue 3, May 1989 and
Supplement 1, June 1990, "ISDN Access Call Control Switching and Signaling
Requirements (Layer 3)."
• Northern Telecom Document No. NIS-S208-4, October 1988, "ISDN Basic Rate
Access User Network Interface Specification."
• AT&T Document 5D5-900-311, Issue 1.01, March 1989, "5ESS Switch ISDN
Basic Rate Interface Specification, 5E5 Generic Program."