Nortel Networks 553-3001-211 manual Codec

Page 36 of 894 Overview

Figure 4

Typical analog line interface unit block diagram

		Balancing Network
DS-30X or		Variable gain	Impedance
SL-1 network
loop		filters	matching	Tip
Tx PCM			transformer
		2-wire	Line
Rx PCM	CODEC	to	interface
		4-wire	and
		conversion	protection
				Ring
Off-hook			Off-hook
			detector
			Ring voltage
Ringing			Ringing
			circuit
Message			Message
waiting
			waiting
			circuit
			–150V dc	553-6153

553-3001-211 Standard 2.00 September 2004