These slowly replaced the spark transmitters in high power radiotelegraphy stations. After this it became the standard method of receiving CW radiotelegraphy. Routine communications was by radiotelegraphy to Angmagssalik. Therefore, it was the most common type used in commercial radiotelegraphy stations. After this time FBOs were a standard part of radiotelegraphy receivers. Its use spread to ordinary telegraph lines and radiotelegraphy radio receivers. So spark transmitters could not transmit sound, and instead transmitted information by radiotelegraphy. All communication to and from Isachsen Station was via shortwave radio radiotelegraphy. During poorer radio propagation periods morse code radiotelegraphy had to be used. Deep-ocean weather ships had to await the commencement of radiotelegraphy. The majority of glowbug transmitters are designed to be used in the CW radiotelegraphy mode. Signals can be sent by flaghoist, signal lamp ("blinker"), flag semaphore, radiotelegraphy, and radiotelephony. Allied airships and military aircraft also made some use of radiotelegraphy. Practical radiotelegraphy communication systems were developed by Marconi beginning in 1895. On 29 May 1902 he was operating this device, listening to a radiotelegraphy station.