ITU-T E.121-1989
Pictograms and Symbols to Assist Users of the Telephone Service - Telephone Network and ISDN - Operation@ Numbering@ Routing and Mobile Service (Study Group II) 11 pp

Standard No.

ITU-T E.121-1989

Release Date

1989

Published By

ITU-T - International Telecommunication Union/ITU Telcommunication Sector