Keyboard for telephone or ciphering apparatus, can be in form of either 10 numerical or 26 alphabetical keys

摘要

The keyboard has each key marked with a digit or a letter. A user can compose numbers (telephone numbers of secret codes) comprised of digits and/or letters. Two types of keyboard can be used: a) a keyboard with 10 numerical keys, each of them being marked with a digit and several letters, b) a keyboard with 26 alphabetical keys, each of them being marked with a letter and with digits shared between the keys.