Nortel Networks Circuit Card - Manual (Page 265)

NT5D33 and NT5D34 Lineside E1 Interface cards Page 265 of 906
Circuit Card Description and Installation
E1 Coding
The LEI is capable of interfacing with LTU equipment using either AMI or
HDB3 coding. Make the selection for this dip switch position based on the
type of coding the LTU equipment supports.