This Recommendation defines designations and additional information intended primarily for human-to-human communication between various Operators, i.e., network operators or service providers.
ITU-T M.1400-2006 history
2015ITU-T M.1400-2015 Designations for interconnections among operators' networks (Study Group 2)
2013ITU-T M.1400-2013 Designations for interconnections among operators' networks Study Group 2
2006ITU-T M.1400-2006 Designations for interconnections among operators' networks Study Group 4