Other types of keyboards, known as "numeric keypads", are the
Calculator keypad (with the 123 keys near the bottom)
the CCITTtelephone keypad[?] (with the 123 keys at the top), arguably the most common keyboard layout in the world, with roughly 700,000,000 telephones in the world (estimated, as of 1994).
... palate[?]) (c, ch, j, jh, ~n)
Retroflex[?] (roughly the place of articulation of English alveolars like t, but with the tongue curled back) (t, th, d, dh, n)
Dental ...