In the ITU-T International X. 121 format, the sets of digits that comprise the complete address of the data terminal end point. Note: For an NTN that is not part of a national integrated numbering format, the NTN is the 10 digits of the ITU-T X. 25 14-digit address that follow the Data Network Identification Code (DNIC. ) When part of a national integrated numbering format, the NTN is the 11 digits of the ITU-T X. 25 14-digit address that follow the DNIC.