Nortel Networks BCM50 manual Digital trunk types and descriptions Sheet 1

Appendix K System region attributes 237

Digital trunk types

Table 60 provides a description of the types of digital trunk types.

Note that some of these line types are available only when specific regions are chosen.

Table 60 Digital trunk types and descriptions (Sheet 1 of 2)

Digital trunk	Description
types
T1/E1	Digital line that carries data on 24 channels at 1.544 Mbps (North American); 30 channels
	at 2,048 Mbps (Europe)
	Loop, E&M, DID and ground start lines are also versions of T1 lines.
	You can program auto-answer T1 loop start, T1 E&M trunks, T1 DID, T1 ground start
	trunks, PRI and IP trunks to map to target lines to provide for attendant bypass (calling
	directly to a department or individual) and line concentration (one trunk can map onto
	several target lines).
DID	This is a type of T1 trunk line that allows an outside caller to dial directly into a line on the
	BCM50.
Loop	This is a type of T1 line. This type of line is used on systems where the service provider
	supports disconnect supervision for the digital loop start trunks.
	These trunks provide remote access to the Business Communications Manager from the
	public network. This trunk must have disconnect supervision to allow the trunk to be set to
	auto-answer, which provides the remote access portal.
Ground	T1-groundstart trunk
	These lines offer the same features as loop start trunks, but are used when the local
	service provider does not support disconnect supervision for digital loop start trunks.
	Ground start trunks work with T1 only. By configuring lines as ground start, the system
	recognizes when a call is released at the far end.
E&M	T1 and E&M. This type of trunk line is used to create simple network connections to other
	phone systems.
	This trunk always operates in a disconnected supervised mode.
PRI	ISDN interface with 23 B channels and 1 D channel at 1.544 Mbps (in Europe: 30
	B-channels and 1 D-channels at 2.048 Mbps).
	These lines give you incoming and outgoing access to an ISDN network and are
	auto-answer trunks.
BRI	ISDN loop that provides both T and S reference point loops.
	These loops can support both network (T and S loops) and terminal equipment (S loop)
	connections.
	This type of line provides incoming and outgoing access to an ISDN network. ETSI ISDN
	BRI is the European Telecommunications Standards Institute specification for BRI ISDN
	service. BRI provides two bearer B-channels operating at 64 kbits/s and a data D-channel
	which operates at 16 kbits/s. The D-channel is used primarily to carry call information. Like
	loop start trunks, BRI lines can be configured as manual-answer or auto-answer.
DASS2	(British) Trunk provides multi-line IDA interconnection to the British Telecom network.

BCM50 Installation and Maintenance Guide