In T1 mode the primary rate interface is able to work with different line codes. e1-hdb3(1) High Density Bipolar 3 Level Coding This is the only valid linecoding for E1 t1-b8zs(2) Bipolar 8 Zero Substitution B8ZS refers to the use of a specified pattern of normal bits and bipolar violations which are used to replace a sequence of eight zero bits t1-ami(3) Alternating Mark Inversion. AMI refers to a mode wherein no zero code suppression is present and the line encoding does not solve the problem directly. In this application, the higher layer must provide data which meets or exceeds the pulse density requirements, such as inverting HDLC data. t1-linecodes can only be set when pmxIfLayer1Mode is t1 e1-linecodes can only be set when pmxIfLayer1Mode is e1 The default linecode for t1 is t1-b8zs