Overview
1-93610-A2-GB41-60 March 1999
DBM Types
Three dial backup modules (DBMs) are available. A
DBM is optional and provides an alternate data path in
case the digital connection fails. Each of the three DBM
types listed below occupy one slot in the COMSPHERE
3000 Series Carrier.

DBM-V

A DBM-V is used for point-to-point dial backup and
provides multipoint dial backup with a digital bridge. The
DBM-V provides a carrier-mounted, 14.4 kbps V.32bis
module that is compatible with the DBM associated with
3600 Series DSUs and with a COMSPHERE 6700 or
6800 Series NMS.

DBM-S

A DBM-S provides the capability to utilize the 4-wire
switched 56 kbps digital service to back up a failed
multipoint DDS circuit via a digital bridge. It is
particularly useful in an MCMP backup environment. The
DBM-S can be used on switching services that are
compatible with AT&T, MCIr, and US SPRINTr using
dedicated 4-wire access.

DBM-D

A DBM-D provides the capability to utilize the 2-wire
switched 56 kbps digital service to back up a failed
multipoint DDS circuit via a digital bridge. It is
particularly useful in an MCMP backup environment. The
DBM-D can be used on switching services that are
compatible with Northern Telecom’s DataPatht service
using dedicated 2-wire access.
NOTE
References to DBM operation in
this guide also apply to a DBM-V,
DBM-S, or DBM-D.
Government Requirements
For the Government Requirements and specific
instructions pertaining to connection to the telephone
network, refer to the COMSPHERE 3600 Series Data
Service Units, Models 3610 and 3611, User’s Guide.
Equipment Warrantyand Support
For the Equipment Warranty and Support instructions,
refer to the COMSPHERE 3600 Series Data Service
Units, Models 3610 and 3611, User’s Guide.
NOTE
If the DSU-TDM or DSU-MCMP
was ordered as an integrated
unit and needs repair, contact
your service representative;

do

not remove the TDM or MCMP

from the DSU

.