Historical throwbacks

I sometimes hear what sounds to me like a telegraph operator keying morse at a very respectable rate.  It turns out to be a young person energetically keying an SMS message into their cellphone.  That young person might be surprised to learn that their great-parents would have been familiar with the mapping of letters to digits on the phone dial.
 
Seen on 335 Caledonian Road in 2002.
 
The director system using a three letter exchange code was introduced in London in 1922.  And letters appeared on dials probably a few years before that in the USA.
 
The arrangement of letters on the US dial, given in this Wikipedia entry, is the same as on cell phones except that Q and Z are omitted - probably to give a neat three letters per digit arrangement.  The UK dial was slightly different.
 
While on the subject of dials, on computer numeric keypads and on calculators the 0 (zero) key is usually near the 1 key.  But on telephone keypads the 0 key is near 9.  This is a throwback to the rotary dial where 0 was next to 9.  0 sent ten pulses.  (A few countries did have different arrangements but 0 next to 9 was the most widespread.)
 
Also on computer numeric keypads and on calculators the 1 to 9 keys are usually in a square with 789 on the top row.  But on telephone keypads the top row is 123.  I do not think this difference can be blamed on the rotary dial.