ITU-T Rec. E.121 (02/1995) – PICTOGRAMS, SYMBOLS AND ICONS TO ASSIST USERS OF THE TELEPHONE SERVICE
FOREWORD
CONTENTS
SUMMARY
1 Scope
2 References
3 Definitions
4 Abbreviations
5 Elements of symbols and pictograms
    5.1 Use of elements
    5.2 Guidelines for design
6 Graphical representation of tones
    6.1 Temporal structure
    6.2 Pitch variation in a tone
    6.3 Tone quality
    6.4 Loudness variation in the tone
7 Pictograms to aid location of service
    7.1 Symbol for telephone
    7.2 Symbol for information
    7.3 Symbol for facsimile
    7.4 Symbol of access for the physically handicapped
    7.5 Symbol for special facilities for the hard of hearing
    7.6 Symbol for special facilities for the deaf
8 Pictograms to aid identification of information
9 Pictograms to aid in the use of a public service
10 Pictogram to aid identification of telephone subscriber services and telephone functions
11 Guidelines for testing
References