Nortel Networks BCM1000 manual Digital Trunk media bay module, Front view, DTM LED functions

38Chapter 2 Telephony hardware

Digital Trunk media bay module

The Digital Trunk media bay module (DTM) connects a standard digital PSTN line to the Business Communications Manager using either a digital or PRI line.

•On North American Business Communications Manager systems, the DTM connects to a T1 or PRI line. With a T1 line, you can add a maximum of 24 digital telephone lines. With a PRI line, you can add a maximum of 23 digital telephone lines.

•On International Business Communications Manager systems, the DTM connects to an ETSI or PRI digital line. With an ETSI or PRI line, you can add a maximum of 30 digital telephone lines.

The front bezel of the DTM has a RJ48C connector that connects the DTM to the service provider connection point. The faceplate also has a set of loopback connectors you can use to run loopback tests. For details on loopback tests, refer to the Business Communications Manager Programming Operations Guide. Figure 15 shows the front of the module.

Figure 15 DTM module LEDs and connectors, front view

Power LED
Status LED	Front view
In Service LED
Loopback Test LED
Continuity Loopback
Receive LEDs
Transmit LEDs
Loopback
RJ48C digital telephone line connector

Table 4 provides a description of the function for each DTM LEDs.

Table 4 DTM LED functions

LED label		Function
	(Power)	On indicates that the DTM is receiving +5 volts.
	(Status)	On indicates there is data communication between the DTM and the MSC card.
In Service		Flashing indicates that the T1, ETSI or PRI trunks are out of service because a
		loopback test is running or the DTM is initializing.
Loopback		On indicates a continuity loopback test is running.
Receive Alarm		On indicates a problem with the received digital transmission. This half-duplex link
		does not work.
Receive Error		On indicates a small error as a result of degraded digital transmission. Possible
		causes are an ohmic connection, water ingress, or too long a loop.

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