I was somewhat surprised this book exists. It's cumbersome title is New Official Vocabulary For Telegrams In Preconcerted Language Prepared In Accordance With The Decisions Of The International Telegraph Conference At Budapest, By The International Office Of Telegraph Administrations. Lengthy no? It's in the public domain and you can read it here if you feel you need to. It opens with the below diatribe.
The book includes the words of eight languages in alphabetical order without any numbering except for page numbers. The idea was that regulations would require all private telegrams to use only words from this massive list. But this effort was not made to prevent coded messages. The IOTA offered to include more words by request and were contacted by 136 publishers of telegraphic codes to include their vocabularies in this master list. If those words met with regulations they laid out at that meeting in Budapest. This tome contained 256.740 words with an estimate their list would grow to include 1.3 million words.
"The Official Vocabulary has been created with the object of remedying certain abuses and inconveniences which in course of time found their way into the drawing up of telegrams in preconcerted language. Consequently the vocabulary is destined to serve as a guide for the choice of words to be used in this kind of telegraphic correspondence. in order to adapt it exclusively to this use the Offices of the Telegraph Union have charged the International Office with the Elaboration of a second edition, which differs from the first in this, in that it will be a mere list of words, absolutely free from the dispositions and arrangements which might give it the character of a code and permit it to be used as such."
The eight languages included English, Dutch, French, German, Italian, Portugese and Spanish. You certainly could not transmit a message in Russian, Swahili, Mandarin, or even Polish under these constraints. However, you could still transmit "artificial words." Those words could contain up to 10 letters. It's hard to say what all his accomplished.