User's Guide Modem 56

Page 142
AT#N V.25bis Character Encoding
Use the #N command to select either NRZ or NRZI character encoding for V.25bis synchronous
operation.
This command only takes effect when a synchronous V.25bis operating mode is selected.
Before setting the #N command, check which character encoding method is expected by your
computer.
Options
AT#N0 ■ NRZ Character Encoding
AT#N1 NRZI Character Encoding
Range
0-1