TelAutography Teletype Teletype network Teletyping closed-circuit telegraphy code duplex telegraphy electricity facsimile telegraph interrupter key multiplex telegraphy quadruplex telegraphy railroad telegraphy receiver sender simplex telegraphy single-current telegraphy sounder stock ticker submarine telegraphy telegraphics telegraphy teleprinter teletypewriter teletypewriting telex ticker transmitter typotelegraph typotelegraphy wire service