Interconnection for TELEX service was made by dialing a subscriber as in telephone operation. TELEX directories then, as now, gave the call numbers of subscribers. Types of answerback devices were designed in both England and Germany which finally developed into an arrangement whereby the calling subscriber would, after dialing a number, press a special key, the shifted D key—named the “Who-Are-You?” button—which would cause the transmission of a signal code automatically to activate the called teletypewriter mechanism into transmitting its TELEX number.
Further apparatus, a device to punch the code in a tape and a punched-tape-controlled transmitter, was soon added.
The Siemens company also developed and built completely automatic switching equipment for the TELEX system which is used by many telegraph administrations.
Through the cooperation of the companies who were manufacturing teleprinters and associated equipment, the many problems that appeared were eventually solved to improve the apparatus and bring the TELEX system to eventual perfection for worldwide telegraph communications. (At the time of this writing, according to statistics, there are nearly 1,000,000 TELEX subscribers throughout the world.)
One of the problems faced in setting up such a worldwide system was that of standardizing the code and operating speed. At the time of Kleinschmidt’s stay in London in 1930 to close negotiations with Creed for the sale of Morkrum-Kleinschmidt’s foreign rights, he met Mr. Martin Feuerhahn of the German Telegraph Administration who at that time was in conference with Creed and representatives from the British Telegraph Administration as to standardizing on an alphabet and telegraph code for international communications. Mr. Feuerhahn argued for the adoption of the American Murray alphabet and code, stating that he already had the approval and consent of the French, Italian, and Belgian telegraph administrations.
Mr. Feuerhahn and Kleinschmidt spent some hours together. After their return to their respective countries, Kleinschmidt received a letter from Mr. Feuerhahn referring to their talks and stating that he had been in correspondence with Mr. Benjamin of Western Union and Mr. Parker of Bell Laboratories with regard to code and other pertinent matters of standardization so that an International Teleprinter Exchange could be extended into the United States. Another letter dated October 10, 1931, reviewed the aforementioned standardization search.
The Murray alphabet and 7½-unit code were soon adopted and are still in use today in TELEX.
In later years, an association, the Consultative Committee on International Telegraph (CCIT—now the CCITT to include the telephone), was formed and met regularly to discuss problems and to set operating regulations for the TELEX apparatus in an intercommunicating system. The CCITT at this writing is still meeting regularly on worldwide standardization in both telegraph and telephone communications.
TELEX IN THE UNITED STATES AND TWX
In the United States, in November 1931, the Bell Telephone Companies announced an intercommunicating teletypewriter service, called TWX for short (TeletypeWriter eXchange), by which interconnections could be made by a switchboard operator as in telephone service. One of their first advertisements named it a “Telephone Typewriter Service, a service that typewrites by wire, a method of inter-office communication that has the quickness of the telephone, the flexibility of conversation, the accuracy of the typewriter, the authority of the printed word, the permanency of print.”[13] Tape-punching and tape-controlled transmitting apparatus was provided. This service allowed subscribers to carry on a typewritten conversation at a charge less than the cost of a telephone call, whether to local or to distant areas. The maximum speed of this equipment was limited to sixty words per minute.