E.161

E.161 is an ITU-T Recommendation that defines the assignment of the basic 26 Latin letters (A to Z) to the 12-key telephone keypad.[1] Uses for this mapping include:

E.161
A standard E.161 keypad
StatusIn force
Year started2006
Latest version(11/16)
November 2016
OrganizationITU-T
Related standardsG.652, G.8201
Domaintelecommunication
Websitehttps://www.itu.int/rec/T-REC-G.657

ETSI ETS 300 640 and ISO 9995-8 also address this. Language-specific letters (e.g. ü, é, å, ä, ö) as well as other characters (e.g. ‘€’ or ‘@’) are not addressed, which has led to a variety of inconsistent solutions for European languages.[3]

The E.161 layout is primarily based on the layout used on American telephones since the 1930s for telephone exchange names. Until the 1990s, Q and Z were not included in the standard layout, and since the letters served mainly as mnemonic devices, they were not necessary (Q and Z were not used in phonewords); telephones either omitted them, placed Q and Z onto the 1 key, or included Q and Z on the current locations, with PRS on 7 and with WXY on 9, respectively. The development of text messaging on mobile phones, which required the full range of the alphabet, led to the need to standardize locations for Q and Z on mobile devices. E.161 adopted the current layout in response to this.

See also

References

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