Abstract: The invention relates to digital devices, employing a reduced keyboard for text entering. The technical effect of the invention is solving ambiguity of depressed key sequence by using disambiguation system at character level, minimizing a number of entered keystrokes, raising efficiency of inputting both broadly used and special characters of various languages and enabling a user to enter texts by using a touch typing system. Characters 5 of the alphabet are divided into groups 21, 22, 23, depending on its frequency of occurrence in the actual texts. Any character 5 of group 21, comprising “high-frequency” character, is entered by one key-press. As for characters of other groups 22, 23, it is required to select a relevant group 22 or 23, first, and then select a character 5 of same group. Depending on a number of characters in the alphabet and keys on the reduced keyboard, the character groups are split to multiple subgroups 24 (comprising 2-3 characters each).