Comment by avidiax

It was quite common to have a codebook that might list several numbers or words used to substitute for places, individuals, actions, etc.

These also existed for corporate entities. A concern might have their own codebook such that the telegraph office would not be privy to their internal business.

They would also use codebooks as a type of compression, since the telegraph company charged less for sending English words as opposed to enciphered characters, and obviously, there are many uncommon words that could substitute for longer common phrases.

https://en.wikipedia.org/wiki/Codebook

https://en.wikipedia.org/wiki/Commercial_code_(communication...