Nortel Networks 400 4.0 User Manual

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Chapter 2 Introducing the BCM hardware
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provides the functionality of a DTM (T1 digital lines only)
splits the incoming T1 line so that some of the lines are used for voice traffic and some of the 
lines are used for data traffic
provides either the channel service unit (CSU) or data service unit (DSU) functionality to 
support connections to data terminal equipment (DTE), such as a router or a bridge
connects to network devices that support V.35 interfaces
provides end-to-end transparent bit service
supports loopbacks between the BCM system and the internal BCM components, and between 
the BCM system and digital terminal equipment 
 shows the DDIM faceplate LEDs and connectors.
Figure 35   DDIM faceplate LEDs and connectors
BCM400 expansion gateway
The BCM400 expansion gateway is available in standard and redundant configurations for 
BCM400 systems only.
The BCM400 expansion gateway kit (North America only) consists of a BCM400 main unit and 
enough VoIP gateway trunk authorization codes to enable 48 ports of VoIP trunks. The BCM400 
expansion gateway, combined with the BCM400 host system, provides a maximum of 192 TDM 
sets, instead of 160, while communicating to the PSTN through TDM trunks on the expansion 
gateway. The VoIP trunks connect the two systems and allow the BCM400 expansion gateway to 
tandem from IP trunks to the PSTN/TDM trunks (see 
The addition of a second BCM400 expansion gateway provides up to two T1 PSTN trunks. This 
releases enough system resources on the host BCM400 main unit for the addition of 64 digital 
telephones.
RxD
TxD
RTS
CTS
DCD
DSR
TM
10101
Data module serial port
Power LED
Status LED
In Service LED
Loopback test LED
Continuity loopback
Receive LEDs
Transmit LEDs
Loopback
RJ-48C digital telephone line 
connector