SIST ETS 300 640 E1:2003

SIST ETS 300 640 E1:2003 is the Slovenian adoption of ETS 300 640 Edition 1, published by SIST and based on an ETSI European Telecommunications Standard. It specifies how alphabetic letters are assigned to digits on standard telephone keypad arrays for telecommunication terminals, so manufacturers and designers use a common keypad letter layout.

What does SIST ETS 300 640 E1:2003 specify?

SIST ETS 300 640 E1:2003 defines the assignment of alphabetic letters to digits on standard telephone keypad arrays. It applies to public and private terminals, in hardware or software form, and it is focused on terminal design and human factors.

The document is organized into a short set of clauses and one informative annex:

The scope excludes diacritical marks and non-Latin character sets. It also excludes terminals specifically intended for text telephony, which matters when a product must support a different input convention.

What are the key requirements of SIST ETS 300 640 E1:2003?

Clause 4 requires alphabetic letters on standard telephone keypad arrays to follow the familiar international pattern used in ITU-T E.161 and ISO/IEC 9995-8. In practice, this means a terminal should present the same letter-to-digit relationship that users expect from standard telephone keypads, so text entry and letter-based recall work consistently across devices.

The standard applies to any terminal that assigns letters to keypad digits, whether the keypad is physical push button keys or software-based soft keys. For implementers, that means the rule is not limited to one type of handset or console - it covers any interface that behaves like a telephone keypad.

The introduction warns that many existing terminals use different assignments, including some developed for text telephony. Before introducing services that assume this standard layout, designers and service owners should consider the risk of input errors on non-compliant terminals.

Annex A gives human factors guidance for the keypad layout. It says added letters should not reduce the legibility of the digits, and the size and style of the characters should follow the relevant guidance in ETR 116. In practice, labels must stay readable at normal viewing distance.

Annex A also says the presence of letters should not compromise key size or interkey spacing. It points designers to ETR 116 and DTR/HF-02009 for finger-activated keypads, which matters when choosing key pitch and label placement.

The document also aligns the letter assignment with ETS 300 511, ITU-T Recommendation E.161, and ISO/IEC 9995-8. That alignment matters because it supports interoperability across mobile, terminal, and keypad designs.

What terms does SIST ETS 300 640 E1:2003 define?

• standard telephone keypad array - The standard 4 x 3 numeric keypad with digits 0-9 and the * and # symbol keys.
• push button keys - Physical input controls that register a command when pressed.
• soft keys - Physical or software-displayed keys whose function is set by the current application.
• ETS - European Telecommunication Standard.
• ETSI - European Telecommunications Standards Institute.
• ITU-T - International Telecommunication Union - Telecommunication Standardization Sector.
• TC-HF - ETSI Technical Committee "Human Factors".

Who uses SIST ETS 300 640 E1:2003?

SIST ETS 300 640 E1:2003 is used by telephone terminal manufacturers, UI and human factors engineers, and designers of public and private telecommunication terminals. It is also relevant to teams selecting keypad layouts for hardware keypads and software soft keys.

In practice, it helps people decide how to label keypads, how to keep labels readable, and how to avoid mismatches between terminals and services that assume the standard letter assignment.

What changed in SIST ETS 300 640 E1:2003 from the previous edition?

SIST ETS 300 640 E1:2003 is identical to ETS 300 640 Edition 1.

Which standards are used with SIST ETS 300 640 E1:2003?

• ETS 300 511 - Provides the GSM mobile station MMI reference that the letter assignment is harmonized with.
• ETR 116 - Gives human factors guidance for ISDN terminal equipment design, including character displays, labels, keys and pushbuttons.
• ETSI DTR/HF-02009 - Gives characteristics of telephone keypads and guidance for elderly and disabled users.
• ISO/IEC 9995-8 - Defines the allocation of letters to the keys of a numeric keypad.
• ITU-T Recommendation E.161 - Defines the arrangement of figures, letters and symbols on telephones and related devices.

What does the SIST ETS 300 640 E1:2003 document contain?

The document contains a foreword and introduction that explain why ETSI aligned with ITU-T and ISO/IEC practice. Clause 4 and Figure 1 give the keypad letter assignment itself.

Annex A adds practical design guidance on legibility and key size. The front matter also includes the contents, transposition dates, and document history, which help users trace the edition and its adoption.