Count rotary dial pulses in a phone number (including letters)
05AB1E, 19 18 17 15 bytes

AÁ0ªā6+žq÷9š‡þO


Try it online!

This is the first answer to use π. Why use π, you might ask? Well, the letters are associated with 22233344455566677778889999, in order. Notice how most digits repeat 3 times, but 7 repeats 4 times. You could say that each digit repeats (3+1/7) times, on average. I wonder if there’s any number that’s approximately 3+1/7 and takes fewer bytes than 22/7…

This only gives 4 7s, not 4 9s, so we still need to handle Z as a special case.

A               # alphabet (abcdefghijklmnopqrstuvwxyz)
 Á              # rotate right (zabcdefghijklmnopqrstuvwxy)
  0ª            # append 0 (zabcdefghijklmnopqrstuvwxy0)

ā6+             # range [7..33]
   žq÷          # divide by π (22233344455566677778889991010)
      9š        # prepend 9 (922233344455566677778889991010)

‡               # transliterate the implicit input with the two lists above
                # this replaces z → 9, a → 2, … y → 9, 0 → 10
 þ              # remove all non-digits
  O             # sum